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

Conflicts:
- `.github/workflows/build-image.yml`:
  Upstream changed how docker images were built, including how
  they were cached.
  I don't know much about it, so applied upstream's changes.
- `app/controllers/admin/domain_blocks_controller.rb`:
  The feature, that was in glitch-soc, got backported upstream.
  It also had a few fixes upstream, so those have been ported!
- `app/javascript/packs/admin.js`:
  Glitch-soc changes have been backported upstream. As a result,
  some code from `app/javascript/core/admin.js` got added upstream.
  Kept our version since our shared Javascript already has that feature.
- `app/models/user.rb`:
  Upstream added something to distinguish unusable and unusable-because-moved
  accounts, while glitch-soc considers moved accounts usable.
  Took upstream's code for `functional_or_moved?` and made `functional?`
  call it.
- `app/views/statuses/_simple_status.html.haml`:
  Upstream cleaned up code style a bit, on a line that we had custom changes
  for.
  Applied upstream's change while keeping our change.
- `config/initializers/content_security_policy.rb`:
  Upstream adopted one CSP directive we already had.
  The conflict is because of our files being structurally different, but the
  change itself was already part of glitch-soc.
  Kept our version.

app/services/verify_link_service.rb

@@ -28,7 +28,7 @@ class VerifyLinkService < BaseService
 
     links = Nokogiri::HTML(@body).xpath('//a[contains(concat(" ", normalize-space(@rel), " "), " me ")]|//link[contains(concat(" ", normalize-space(@rel), " "), " me ")]')
 
-    if links.any? { |link| link['href'].downcase == @link_back.downcase }
+    if links.any? { |link| link['href']&.downcase == @link_back.downcase }
       true
     elsif links.empty?
       false
@@ -38,6 +38,8 @@ class VerifyLinkService < BaseService
   end
 
   def link_redirects_back?(test_url)
+    return false if test_url.blank?
+
     redirect_to_url = Request.new(:head, test_url, follow: false).perform do |res|
       res.headers['Location']
     end