* recalculate mentions of forwarded messages
In transformEvent(), parse event body back into an EditorModel, and pass this into attachMentions(), so that it actually recalculates mentions.
* refactor ForwardDialog-test.tsx
Refactor test for stripping mentions on forwards to allow for more tests of mention recalculation
* add test to recalculate mention pills
Fails due to not mocking room membership
* fix lint
* fix test: add ability to provide source room stub
Tol Wassman
cbe3eb1709