fix: use correct key names for key codes

[maribethb]

The basics

• I validated my changes

The details

Resolves

Fixes #9741
Fixes #9740

Proposed Changes

• adds a mapping of key code to user-facing key name. this isn't perfect because the keyCode system is not really applicable to non-US layouts, but it's what we've got. the mapping uses Msg keys for keys with text on them and symbols for others.
• adjusts the shortcut formatting utils to use the mapping instead of assuming String.fromCharCode always works, though we do fall back to that if it's a key code we don't know.
• removes internal from the methods that get you the keys from the shortcut name
• changed the name and all references to action to reference shortcuts instead from the shortcuts formatting class. "Action" was a terminology we introduced in the keyboard experiment, but we don't use it elsewhere in core and all of the usage of it here was using it to refer to shortcut names. Best to just use the existing terminology. This is not a breaking change because previously these methods were both unreleased and internal only.

Reason for Changes

• Both we and application owners / plugin authors have various use cases for getting a single key combination to display to users for a given shortcut.

Test Coverage

there weren't any existing tests for the shortcut formatter and i didn't add any, but i can do that tomorrow

Documentation

Additional Information