Let team organizer specify role for each player selection

[cheshire137]

We have a player_selections.role field that's intended to let the organizer specify a role that player is fulfilling in the composition by playing that hero. It's an optional field. We should let the user set it and then, on the composition show page #80, we should make it visible in a subtle way, perhaps on hover as a tooltip.

We need an interface with a text field that the user can set to the role for each player+hero on each point. We need a way for the user to access this text field because there's not room on the page for it to be visible all the time, for every selection.

Like maybe I want Rob to play Mercy not as a primary healer, but as DPS because he's gonna Battle Mercy. Or maybe we need Soldier: 76 as our Healer: 76.

[RobThePM]

Neat idea! Is this for after version 1? You're doing the work, so up to you whenever you want to do it! :)