This commit fixes the selection of message in threads and also applies various refactorings
- improves specs and especially page objects/components
- makes the channel/thread panes responsible of the state
- adds an animationend modifier
- continues to follow the logic of "state" should be displayed as data attributes on component by having a new `data-selected` attribute on chat messages
- better handling of drawer state using chat state manager
- removes various float and topic occurrences to use drawer
- ensures user can chat before doing a lot of chat setup
- fixes a bug which was creating presence errors in tests
- removes dead code
