This is a prerequisite for operations that rely on previous messages, such as reactions.

Remove Abstract component
Convert web component to function component

Use new TS config from @jitsi/eslint
Fix all lint errors

Change scroll to bottom when receive a new message with:
- scroll to bottom if scroll was at the bottom before getting a new message
- keep the scroll in his original position when the scroll position was not at the bottom
- scroll to bottom when open first time the chat

So mobile and web can share logic for grouping chat
messages by sender.