Address problems with hotkeys.

[pixelzoom]

Proposed epic for Q3 2022 ...

Since alt-input is now a standard part of sim development, fix problems related to hotkeys. Some of these are serious.

Issues currently include:
#716
#682
#681
#680

Assigning to @kathy-phet to decide whether this epic should be scheduled for Q3 2022, and who should be assigned.

[zepumph]

Subset of phetsims/scenery#1298

[zepumph]

@jessegreenberg and I want to create a more general HotKey class and manager that knows about all keys registered, and delivers a consistent API.

[marlitas]

This issue is here to manage hotkey work and now we have a Monday board to track that. Any remaining work is already tracked in other issues. Closing.