Notification rework: known and reported issues

[bmarty]

• [x] Launcher Icon badge is not correct (value is always 3 on some device)
• [x] There is no "mark as read" action, for each room (and/or for all rooms?)
• [x] If notification contains several rooms, if I dismiss them one by one quite fast, finally they all disappear, even if all rooms have not been dismissed => not reproduced
• [x] Quick Reply (compat mode): sending messages with enter doesn't seem to work, even if the setting is on. It may be have forgotten in #3019
• [x] Notifications are not displayed on watches running WearOS => notification was disabled on the watch for this app
• [x] Use Person to display user Avatar (require support lib upgrade to 28)
• [x] Time of notification for a room is not correct. Should correspond to last message event date

[bmarty]

Done