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

Conflicts:
- `app/lib/formatter.rb`:
  Upstream completely refactored the formatting code and removed that file,
  while glitch-soc had code for Markdown and HTML toots.
  Took upstream code, glitch-soc changes will be re-implemented on top of the
  refactored classes in a later commit.
- `app/models/status.rb`:
  Upstream refactored status edit handling and moved code to
  `app/models/concerns/status_snapshot_concern.rb`.
  Applied glitch-soc's changes to that file.
- `app/serializers/activitypub/note_serializer.rb`:
  Not really a conflict, just a line added too close to one modified by
  glitch-soc.
  Applied upstream changes while keeping the glitch-soc-modified one.
- `app/services/update_status_service.rb`:
  Not really a conflict, upstream modified a line adjacent to one added by
  glitch-soc.
  Applied upstream changes while keeping the glitch-soc line.
- `app/views/statuses/_simple_status.html.haml`:
  Upstream refactored formatting, glitch-soc changed the markup slightly.
  Applied upstream changes.
- `spec/lib/formatter_spec.rb`:
  Upstream completely refactored the formatting code and removed that file,
  while glitch-soc had code for Markdown and HTML toots.
  Took upstream code, glitch-soc changes will be re-implemented on top of the
  refactored classes in a later commit.

app/serializers/rest/status_serializer.rb

@@ -1,6 +1,8 @@
 # frozen_string_literal: true
 
 class REST::StatusSerializer < ActiveModel::Serializer
+  include FormattingHelper
+
   attributes :id, :created_at, :in_reply_to_id, :in_reply_to_account_id,
              :sensitive, :spoiler_text, :visibility, :language,
              :uri, :url, :replies_count, :reblogs_count,
@@ -73,7 +75,7 @@ class REST::StatusSerializer < ActiveModel::Serializer
   end
 
   def content
-    Formatter.instance.format(object)
+    status_content_format(object)
   end
 
   def url