Sometimes, the chat list would jump without the user scrolling:
- During intial loading of a room content, i.e. when it is expected
that the list stays scrolled to bottom
- During loading of messages after jumping to a linked message
With this commit, the target event is repeatedly scrolled to upon list
changes until the users scroll themselves, to avoid above scenarios.
Change-Id: Iabbe76832e7e68686431b0baed9356c88eb50901
b808d8b464