Based on previous investigations into the scope {T259700}, add bracket matching to the syntax highlighting feature in the the 2017 and 2010 wikitext editors. **Implement this only on the beta cluster; the release to wikis will be scheduled for a later date. **
**Scope**
* **Implement in both 2017 Wikitext editor (source view inside VE) and the 2010 wikitext editor.**
* It has already been raised that syntax highlighting does not work in RLT (see T170001). For now, set these issues aside.
* It has also been raised that bracket matching might be particularly difficult in some non-latin writing systems, particularly Japanese and Chinese, which use IME. Solving this issue is also not part of the scope.
See also the initial investigation for more detail: {T254976}
**Requirements:**
[] Load addon scripts.
[] Change highlighting styles. Matched and unmatched brackets should have white text color (Base100). Matched bracket character should have a gray background color (Base20), unmatched brackets should have a red background (Red30). Needs some cleanup, an upstream style is commented out when it should be overridden.
[] Fix bracket-matching logic to consistently detect all types of brackets, in each configuration. Currently (, {, [ each highlight but not in every situation and it's not yet clear what is causing this. Possibly add < as well. Must include tests.
[] Fix VisualEditor "new wikitext" integration breaking the `cursorActivity` event.
**Nice to have:**
[] Fix bracket-matching to detect and highlight "{{" and "[[" as pairs.
**Mocks:**
{F32242208}
{F32242211}