- Added a standalone brace smart indenter that listens to `ITextBuffer` changed events to determine when a brace completion event needs to be handled.
- Added methods to deal with getting document trackers from `ITextBuffer`s.
- Added a `BraceSmartIndenterTest` and `BraceSmartIndenterIntegrationTest` to verify all parts of the smart indenter.
- Moved private test infrastructure classes into their own files and expanded on their functionality to enable the brace completion smart indent scenarios.
#1538