[Chests Anywhere] add custom hotkeys for chests

[Pathoschild]

Let the player specify a custom hotkey sequence that opens a specific chest (e.g. CTRL + M for monster loot).

Requested on the forums.

[Pathoschild]

Mockup:

Pressing the 'set' button would show an overlay with text like this:

Press the buttons you want to use as a hotkey (hold down multiple keys to set a multi-key shortcut).

Probably have a 'clear' button appear when a hotkey is set.