Add full support for Mac-specific keyboard layouts

[Keavon]

Windows and Linux use the standard keyboard layout. Mac uses Cmd instead of Ctrl. For example, copy (CtrlC) is CmdA on a Mac. Mac also uses Option instead of Alt. We need two different versions of our key bindings depending on whether it's Mac or non-Mac.

This is probably an important feature before we launch at the end of Sprint 5 with version 0.1.

• Rust (Input Preprocessor/Input Mapper)
• Rust (menu bar)
• Rust (tooltips)
• Rust (hints) - temporary solution to override the displayed hint on Macs, eventually should be replaced with Refactor the "actions" system into a unified and capable "commands" system #741 (also related: Replace hint Rust -> JS data with a widget layout #739)
• TypeScript
• Vue (event modifiers, key aliases, and system modifier keys - some progress in Make Vue modifier keys work on the Mac keyboard layout #419)

[Keavon]

A related consideration: enable and disable specific keyboard shortcuts when the keyboard lock API is active or inactive.