Initial set of changes to move encoding the related content client side.
- Added HtmlEncoded flag to ChatMessage.
- Removed linkification and content provider logic.
Added content providers back and removed transforming urls on the server.
Added client side linkification.
Added room link conversion client side.
Move multiline replacement logic to client side.
Remove hashtag link logic.
Renamed TextTransform to UrlExtractor.
Removed tests that don't matter anymore.
process topics and welcome messages.