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

Conflicts:
- `README.md`:
  Upstream README has been changed, but we have a completely different one.
  Kept our `README.md`.
- `lib/sanitize_ext/sanitize_config.rb`:
  Upstream added support for more incoming HTML tags (a large subset of what
  glitch-soc accepts).
  Change the code style to match upstream's but otherwise do not change our
  code.
- `spec/lib/sanitize_config_spec.rb`:
  Upstream added support for more incoming HTML tags (a large subset of what
  glitch-soc accepts).
  Kept our version, since the tests are mostly glitch-soc's, except for cases
  which are purposefuly different.

spec/validators/email_mx_validator_spec.rb

@@ -41,6 +41,22 @@ describe EmailMxValidator do
       expect(user.errors).to_not have_received(:add)
     end
 
+    it 'adds an error if the TagManager fails to normalize domain' do
+      double = instance_double(TagManager)
+      allow(TagManager).to receive(:instance).and_return(double)
+      allow(double).to receive(:normalize_domain).with('example.com').and_raise(Addressable::URI::InvalidURIError)
+
+      user = double(email: 'foo@example.com', errors: double(add: nil))
+      subject.validate(user)
+      expect(user.errors).to have_received(:add)
+    end
+
+    it 'adds an error if the domain email portion is blank' do
+      user = double(email: 'foo@', errors: double(add: nil))
+      subject.validate(user)
+      expect(user.errors).to have_received(:add)
+    end
+
     it 'adds an error if the email domain name contains empty labels' do
       resolver = double