* Fix BackfillAdminActionLogs post-deployment migration

* Improve migration tests

* Backfill admin action logs again

As pointed out by https://github.com/mastodon/mastodon/pull/21297#discussion_r1028372193
at least one of our dependencies already dropped support for Ruby 2.6, and we
had removed Ruby 2.6 tests from the CI over a year ago (#16861).

So stop advertising Ruby 2.6 support, bump targeted version, and drop some
compatibility code.

* Reduce redis cache store connect timeout from default 20 seconds to 5 seconds

* Log cache store errors

Fix #19156

Fixes #19133

The Blurhash library used by Mastodon requires an input encoded as 24
bits raw RGB data. The conversion to raw RGB using Imagemagick did not
previously specify the desired bit depth. In some situations, this leads
Imagemagick to output in a pixel format using less bpp than expected.
This then manifested as segfaults of the Sidekiq process due to
out-of-bounds read, or potentially a (highly noisy) memory infoleak.

Fixes #19235.

ENABLE_STARTTLS is designed to replace ENABLE_STARTTLS_AUTO by accepting
three values: 'auto' (the default), 'always', and 'never'. If
ENABLE_STARTTLS isn't provided, we fall back to ENABLE_STARTTLS_AUTO. In
this way, this change should be fully backwards compatible.

Resolves #20311

* Add tests

* Fix crash when trying to display orphaned action logs

* Add migration for older admin action logs

* Fix mastodon:setup not setting the admin's role properly

* Set contact username when creating admin account in mastodon:setup

Fix #19152

* Add a more descriptive PrivateNetworkAddressError exception class

* Remove unnecessary exception class to rescue clause

* Remove unnecessary include to JsonLdHelper

* Give more neutral error message when too many webfinger redirects

* Remove unnecessary guard condition

* Rework how “ActivityPub::FetchRemoteAccountService” handles errors

Add “suppress_errors” keyword argument to avoid raising errors in
ActivityPub::FetchRemoteAccountService#call (default/previous behavior).

* Rework how “ActivityPub::FetchRemoteKeyService” handles errors

Add “suppress_errors” keyword argument to avoid raising errors in
ActivityPub::FetchRemoteKeyService#call (default/previous behavior).

* Fix Webfinger::RedirectError not being a subclass of Webfinger::Error

* Add suppress_errors option to ResolveAccountService

Defaults to true (to preserve previous behavior). If set to false,
errors will be raised instead of caught, allowing the caller to be
informed of what went wrong.

* Return more precise error when failing to fetch account signing AP payloads

* Add tests

* Fixes

* Refactor error handling a bit

* Fix various issues

* Add specific error when provided Digest is not 256 bits of base64-encoded data

* Please CodeClimate

* Improve webfinger error reporting

* Fix typos

Found via `codespell -q 3 -S ./CHANGELOG.md,./AUTHORS.md,./config/locales,./app/javascript/mastodon/locales -L ba,keypair,medias,pixelx,ro`

* Follow-up typo fix

* Add '--days' option to tootctl media refresh

* Fix undefined scope

Minimal adjustments have been made to the short description so that it logically follows the long description

* Add customizable user roles

* Various fixes and improvements

* Add migration for old settings and fix tootctl role management

* Add model for custom filter keywords

* Use CustomFilterKeyword internally

Does not change the API

* Fix /filters/edit and /filters/new

* Add migration tests

* Remove whole_word column from custom_filters (covered by custom_filter_keywords)

* Redesign /filters

Instead of a list, present a card that displays more information and handles
multiple keywords per filter.

* Redesign /filters/new and /filters/edit to add and remove keywords

This adds a new gem dependency: cocoon, as well as a npm dependency:
cocoon-js-vanilla. Those are used to easily populate and remove form fields
from the user interface when manipulating multiple keyword filters at once.

* Add /api/v2/filters to edit filter with multiple keywords

Entities:
- `Filter`: `id`, `title`, `filter_action` (either `hide` or `warn`), `context`
  `keywords`
- `FilterKeyword`: `id`, `keyword`, `whole_word`

API endpoits:
- `GET /api/v2/filters` to list filters (including keywords)
- `POST /api/v2/filters` to create a new filter
  `keywords_attributes` can also be passed to create keywords in one request
- `GET /api/v2/filters/:id` to read a particular filter
- `PUT /api/v2/filters/:id` to update a new filter
  `keywords_attributes` can also be passed to edit, delete or add keywords in
   one request
- `DELETE /api/v2/filters/:id` to delete a particular filter
- `GET /api/v2/filters/:id/keywords` to list keywords for a filter
- `POST /api/v2/filters/:filter_id/keywords/:id` to add a new keyword to a
   filter
- `GET /api/v2/filter_keywords/:id` to read a particular keyword
- `PUT /api/v2/filter_keywords/:id` to edit a particular keyword
- `DELETE /api/v2/filter_keywords/:id` to delete a particular keyword

* Change from `irreversible` boolean to `action` enum

* Remove irrelevent `irreversible_must_be_within_context` check

* Fix /filters/new and /filters/edit with update for filter_action

* Fix Rubocop/Codeclimate complaining about task names

* Refactor FeedManager#phrase_filtered?

This moves regexp building and filter caching to the `CustomFilter` class.

This does not change the functional behavior yet, but this changes how the
cache is built, doing per-custom_filter regexps so that filters can be matched
independently, while still offering caching.

* Perform server-side filtering and output result in REST API

* Fix numerous filters_changed events being sent when editing multiple keywords at once

* Add some tests

* Use the new API in the WebUI

- use client-side logic for filters we have fetched rules for.
  This is so that filter changes can be retroactively applied without
  reloading the UI.
- use server-side logic for filters we haven't fetched rules for yet
  (e.g. network error, or initial timeline loading)

* Minor optimizations and refactoring

* Perform server-side filtering on the streaming server

* Change the wording of filter action labels

* Fix issues pointed out by linter

* Change design of “Show anyway” link in accordence to review comments

* Drop “irreversible” filtering behavior

* Move /api/v2/filter_keywords to /api/v1/filters/keywords

* Rename `filter_results` attribute to `filtered`

* Rename REST::LegacyFilterSerializer to REST::V1::FilterSerializer

* Fix systemChannelId value in streaming server

* Simplify code by removing client-side filtering code

The simplifcation comes at a cost though: filters aren't retroactively
applied anymore.

- Add rake task for generating Apple/Android icons and favicons from SVG
- Add rake task for generating PNG icons and logos for e-mails from SVG
- Remove obsolete Microsoft icons and configuration
- Remove PWA shortcut icons

Fixes #18342

* Bump version to 3.5.2

* Change some entries to be more clear

* Add some extra notes

* Fix line wrap

Co-authored-by: Eugen Rochko <eugen@zeonfederated.com>