Prior to this commit we were loading a large number of thread messages without any pagination. This commit attempts to fix this and also improves the following points:
- code sharing between channels and threads:
Attempts to reuse/share the code use in channels for threads. To make it possible part of this code has been extracted in dedicated helpers or has been improved to reduce the duplication needed.
Examples of extracted helpers:
- `stackingContextFix`: the ios hack for rendering bug when momentum scrolling is interrupted
- `scrollListToMessage`, `scrollListToTop`, `scrollListToBottom`: a series of helper to correctly scroll to a specific position in the list of messages
- better general performance of listing messages:
One of the main changes which has been made is to remove the computation of visible message during scroll, it will only happen when needed (update last read for example). This constant recomputation of `message.visible` on intersection observer event while scrolling was consuming a lot of CPU time.
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
