1. Display avatar in top bar next to channel name and description.
2. Edit icon appears on hover.
3. Clicking on the Edit icon opens file browser to upload a new avatar.
4. Certain file types are allowed.
5. Avatar can only be changed for group chat by any member of the channel.
6. For channel it can be done with admin rights.
7. Disable uploading text from file uploader in this case.
Also show avatar of channel/chat conversation in chat window.
Author avatar in message list no longer shown im status.
Chat window header color matches new systray color.
task-2684679
[FIX] mail: make chat window header match systray color
Part-of: odoo/odoo#117357