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

Conflicts:
- `app/controllers/api/v1/statuses_controller.rb`:
  Conflict due to upstream adding a new parameter (with_rate_limit),
  too close to glitch-soc's own additional parameter (content_type).
  Added upstream's parameter.
- `app/services/post_status_service.rb`:
  Conflict due to upstream adding a new parameter (rate_limit),
  too close to glitch-soc's own additional parameter (content_type).
  Added upstream's parameter.
- `app/views/settings/preferences/appearance/show.html.haml`:
  Conflict due to us not exposing theme settings here (as we have
  a different flavour/skin menu).
  Took upstream change, while still not exposing theme settings.
- `config/webpack/shared.js`:
  Coding style fixes for a part we have rewritten.
  Discarded upstream changes.

Gemfile

@@ -49,7 +49,7 @@ gem 'omniauth-saml', '~> 1.10'
 gem 'omniauth', '~> 1.9'
 
 gem 'discard', '~> 1.1'
-gem 'doorkeeper', '~> 5.2'
+gem 'doorkeeper', '~> 5.3'
 gem 'fast_blank', '~> 1.0'
 gem 'fastimage'
 gem 'goldfinger', '~> 2.1'
@@ -92,7 +92,7 @@ gem 'simple-navigation', '~> 4.1'
 gem 'simple_form', '~> 5.0'
 gem 'sprockets-rails', '~> 3.2', require: 'sprockets/railtie'
 gem 'stoplight', '~> 2.2.0'
-gem 'strong_migrations', '~> 0.5'
+gem 'strong_migrations', '~> 0.6'
 gem 'tty-command', '~> 0.9', require: false
 gem 'tty-prompt', '~> 0.20', require: false
 gem 'twitter-text', '~> 1.14'