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.

app/javascript/styles/mastodon/rich_text.scss

@@ -0,0 +1,64 @@
+.status__content__text,
+.e-content,
+.reply-indicator__content {
+  pre,
+  blockquote {
+    margin-bottom: 20px;
+    white-space: pre-wrap;
+    unicode-bidi: plaintext;
+
+    &:last-child {
+      margin-bottom: 0;
+    }
+  }
+
+  blockquote {
+    padding-left: 10px;
+    border-left: 3px solid $darker-text-color;
+    color: $darker-text-color;
+    white-space: normal;
+
+    p:last-child {
+      margin-bottom: 0;
+    }
+  }
+
+  & > ul,
+  & > ol {
+    margin-bottom: 20px;
+  }
+
+  b,
+  strong {
+    font-weight: 700;
+  }
+
+  em,
+  i {
+    font-style: italic;
+  }
+
+  ul,
+  ol {
+    margin-left: 2em;
+
+    p {
+      margin: 0;
+    }
+  }
+
+  ul {
+    list-style-type: disc;
+  }
+
+  ol {
+    list-style-type: decimal;
+  }
+}
+
+.reply-indicator__content {
+  blockquote {
+    border-left-color: $inverted-text-color;
+    color: $inverted-text-color;
+  }
+}