Bring "Pin rooms with missed notifications" & "Pin rooms with unread messages" from Riot Mobile to other screens & clients

[Mikaela]

My issue is mainly documented at element-hq/element-web#4484 but it's only reported against Riot-Web favourites while I can see this issue starting to affect other tags and Riot Android too.

Currently I have 33 favourites and 128 rooms and because of the previously mentioned issue I am having difficulties following other rooms than favourites.

With Riot Android, when I move out of the home screen and to rooms, the latest room with any activity is on top meaning even join/leave from dead IRC room causes the room to be thrown on top of the list and I have to start scrolling down as I try to read rooms.

I wish the notified and unread rooms would stay on top and if I happened to need a room which I just read, I would simply scroll down to the read rooms.