Kick user from cell code editor in multiplayer

[luke-quadratic]

Consistent annoyance in the multiplayer experience, other tools solve it by having a prompt to kick out other users and take over. Clicking take over cell would give you access to the cell from your teammate (bridge solution until code editing is collaborative down the line)

[davidkircos]

Related: sometimes the root cell is locked but if you try and open a code cell from an output cell it won't show you that it's locked or it shows the message at the top cell, and you can't necessarily see it.

[ddimaria]

I had a similar annoyance this morning. Should we add some rules to this? An owner can kick anyone out, but editors can't kick owners out?

[ddimaria]

Note: kicking someone out could result in code loss. @davidfig can you confirm?

[davidfig]

This could result in changes being lost since we only save when you run. Multi-editors in the code cell would solve this without needing to kick people out.