* Add option to make the landing page be /about even when trends are enabled

* Restablish /explore as landing page by default

* Change “Translate” button to only show up when a translation backend is configured

Fixes #19346

* Add `translation` attribute to /api/v2/instance to expose whether the translation feature is enabled

Fixes #19328

Cherry-picked d2528b26b6

Conflicts:
- `app/serializers/initial_state_serializer.rb`:
  Upstream changed stuff, we had extra attributes.
  Applied upstream changes while keeping our extra attributes.
- `app/serializers/rest/instance_serializer.rb`:
  Upstream actually moved that to `app/serializers/rest/v1/instance_serializer.rb`,
  so updated that file by keeping our extra attributes, and took upstream's
  version of `app/serializers/rest/instance_serializer.rb`.
- `spec/views/about/show.html.haml_spec.rb`:
  Took upstream's version.

* Remove timeline preview link from nav panel when not signed-in

* Always enable server stats

* Add customizable user roles

* Various fixes and improvements

* Add migration for old settings and fix tootctl role management

Fixes #13882

Fix #1288

Fix #9031
Fix #7913

Fix #9031
Fix #7913

* Add option to disable blurhash previews

* Update option text

* Change options order

* Add responsive panels to the single-column layout

* Fixes

* Fix not being able to save the preference

* Fix code style issues

* Set max-height on the compose textarea and add a link to relationship manager

* config: Add GITHUB_REPOSITORY for repository name

* config: Add SOURCE_BASE_URL for repository url

* Show source_url and repository name on getting started

* Allow to show a specific status in the admin interface

* Let the front-end know the current account is a moderator

* Add admin links to status and account menus

If the current logged-in user is an admin, add quick links to the admin
interface in account and toot dropdown menu. Suggestion by @ashkitten

* Use @statuses.first instead of @statuses[0]

Follow-up to #8766

Fix #7846

- Find friends from Twitter (bridge)
- Invite people (when invites enabled)
- Security (change e-mail/password)
- Developers (create OAuth apps/tokens)

* When advanced search is enabled, show different hint in search popout

* Change "getting started" icon in tabs bar from asterisk to hamburger

* Refactor initial state: "me"

* remove "me" from reducers/meta.js