Some specs have already been added.

Nothing to test.

* Add specs for JsonLdHelper#first_of_value

* Add specs for JsonLdHelper#supported_context?

Fix #340

* Add specs for UnreservedUsernameValidator

* Use instance variable

- Reduce time-to-digest from 20 to 7 days
- Fetch mentions starting from +1 day since last login
- Fix case when last login is more recent than last e-mail
- Do not render all mentions, only 40, but show number in subject
- Do not send digest to moved accounts
- Do send digest to silenced accounts

* Ensure blocked user unfollows blocker if Block/Undo Block are processed out of order

* Add specs for Block causing unfollow and for out-of-order Block + Undo

* Do not LDS-sign Follow, Accept, Reject, Undo, Block

* Do not use LDS for Create activities of private toots

* Minor cleanup

* Ignore unsigned activities instead of misattributing them

* Use status.distributable? instead of querying visibility directly

* Add specs for BlackListedEmailValidator

* Use instance variable

In order to implement tests easier, `#select_tags` created.

* Add pending specs of StatusLengthValidator

* Use instance variable

* Add REST API for creating an account

The method is available to apps with a token obtained via the client
credentials grant. It creates a user and account records, as well as
an access token for the app that initiated the request. The user is
unconfirmed, and an e-mail is sent as usual.

The method returns the access token, which the app should save for
later. The REST API is not available to users with unconfirmed
accounts, so the app must be smart to wait for the user to click a
link in their e-mail inbox.

The method is rate-limited by IP to 5 requests per 30 minutes.

* Redirect users back to app from confirmation if they were created with an app

* Add tests

* Return 403 on the method if registrations are not open

* Require agreement param to be true in the API when creating an account

Fixes #9580

* Add moderation warnings

Replace individual routes for disabling, silencing, and suspending
a user, as well as the report update route, with a unified account
action controller that allows you to select an action (none,
disable, silence, suspend) as well as whether it should generate an
e-mail notification with optional custom text. That notification,
with the optional custom text, is saved as a warning.

Additionally, there are warning presets you can configure to save
time when performing the above.

* Use Account#local_username_and_domain

* Add spec for RelayPolicy

* Add specs for SubscriptionPolicy

* Add specs for SettingsPolicy

* Add specs for TagPolicy

* Add specs for ReportPolicy

* Add failing test for windows-1251 link cards

* Ignore low-confidence CharlockHolmes guesses

Fixes #9466

* Fix no method error when charlock holmes cannot detect charset