M9.1 Improved leave experience for spaces

[t3chguy]

[ShadowJonathan]

Would this recursively apply to all subspaces too?

[t3chguy]

Best effort at this time given that subspaces are as marked "Experimental"

[niquewoodhouse]

@nadonomy sharing this as I think it would benefit from your input - we were using a previous design that gave users options to:

1. leave rooms/subpsaces
2. transfer their role to someone else

But we didn't make this as above because option 2 because, unfortunately, wouldn't have worked at all with the current scope of remaining milestones.

With the one option remaining, presented as a dropdown, it can be easy to miss [1].

So better design would be to expose the options as radio buttons.

[1] As we don't know what kind of space you want to leave, the option to leave all rooms might be a bit too destructive for personal spaces so missing it is pretty bad.

[t3chguy]

(the animations wouldn't really be feasible without investing a decent chunk of time ftr)

[niquewoodhouse]

We're now going ahead with the radio buttons on Android, so feels even more appropriate here.