Merge branch 'main' into glitch-soc/merge-upstream

Conflicts:
- `README.md`:
  Upstream added a link to the roadmap, but we have a completely different README.
  Kept ours.
- `app/models/media_attachment.rb`:
  Upstream upped media attachment limits.
  Updated the default according to upstream's.
- `db/migrate/20180831171112_create_bookmarks.rb`:
  Upstream changed the migration compatibility level.
  Did so too.
- `config/initializers/content_security_policy.rb`:
  Upstream refactored this file but we have a different version.
  Kept our version.
- `app/controllers/settings/preferences_controller.rb`:
  Upstream completely refactored user settings storage, and glitch-soc has a
  different set of settings.
  The file does not directly references individual settings anymore.
  Applied upstream changes.
- `app/lib/user_settings_decorator.rb`:
  Upstream completely refactored user settings storage, and glitch-soc has a
  different set of settings.
  The file got removed entirely.
  Removed it as well.
- `app/models/user.rb`:
  Upstream completely refactored user settings storage, and glitch-soc has a
  different set of settings.
  References to individual settings have been removed from the file.
  Removed them as well.
- `app/views/settings/preferences/appearance/show.html.haml`:
  Upstream completely refactored user settings storage, and glitch-soc has a
  different set of settings.
  Applied upstream's changes and ported ours back.
- `app/views/settings/preferences/notifications/show.html.haml`:
  Upstream completely refactored user settings storage, and glitch-soc has a
  different set of settings.
  Applied upstream's changes and ported ours back.
- `app/views/settings/preferences/other/show.html.haml`:
  Upstream completely refactored user settings storage, and glitch-soc has a
  different set of settings.
  Applied upstream's changes and ported ours back.
- `config/settings.yml`:
  Upstream completely refactored user settings storage, and glitch-soc has a
  different set of settings.
  In particular, upstream removed user-specific and unused settings.
  Did the same in glitch-soc.
- `spec/controllers/application_controller_spec.rb`:
  Conflicts due to glitch-soc's theming system.
  Mostly kept our version, as upstream messed up the tests.

lib/tasks/tests.rake

@@ -53,6 +53,11 @@ namespace :tests do
         puts 'Admin::ActionLog email domain block records not updated as expected'
         exit(1)
       end
+
+      unless User.find(1).settings['notification_emails.favourite'] == true && User.find(1).settings['notification_emails.mention'] == false
+        puts 'User settings not kept as expected'
+        exit(1)
+      end
     end
 
     desc 'Populate the database with test data for 2.4.3'
@@ -98,6 +103,11 @@ namespace :tests do
           (1, 'destroy', 'EmailDomainBlock', 1, now(), now()),
           (1, 'destroy', 'Status', 1, now(), now()),
           (1, 'destroy', 'CustomEmoji', 3, now(), now());
+
+        INSERT INTO "settings"
+          (id, thing_type, thing_id, var, value, created_at, updated_at)
+        VALUES
+          (3, 'User', 1, 'notification_emails', E'--- !ruby/hash:ActiveSupport::HashWithIndifferentAccess\nfollow: false\nreblog: true\nfavourite: true\nmention: false\nfollow_request: true\ndigest: true\nreport: true\npending_account: false\ntrending_tag: true\nappeal: true\n', now(), now());
       SQL
     end