Change routing paths to use usernames in web UI (#16171)

app/controllers/home_controller.rb

app/javascript/mastodon/actions/accounts.js

app/javascript/mastodon/actions/compose.js

app/javascript/mastodon/api.js

app/javascript/mastodon/components/account.js

app/javascript/mastodon/components/hashtag.js

app/javascript/mastodon/components/status.js

app/javascript/mastodon/components/status_action_bar.js

app/javascript/mastodon/components/status_content.js

app/javascript/mastodon/containers/mastodon.js

...javascript/mastodon/features/account/components/header.js

app/javascript/mastodon/features/account_gallery/index.js

...t/mastodon/features/account_timeline/components/header.js

...stodon/features/account_timeline/components/moved_note.js

app/javascript/mastodon/features/account_timeline/index.js

...pt/mastodon/features/compose/components/navigation_bar.js

...t/mastodon/features/compose/components/reply_indicator.js

app/javascript/mastodon/features/compose/index.js

...todon/features/direct_timeline/components/conversation.js

...pt/mastodon/features/directory/components/account_card.js