Tthe key code logic uses the constant `-1` in a number of places. With the latest TS 4.3 nightly build, this causes a compile error since there is no overlap between `-1` and the `KeyCode` enum

This change adds a `-1` value to the `KeyCode` and `ScanCode` enums

windows initial implementation

It was difficult to refactor the ResolvedKeybindings without
also refactoring label creators, as the null checks where handled in the
label generation.

More manual conversion of index based for loops to for-of loops

As a start to support key chords of longer than two parts,
modifying the internal structure of ChordKeybinding to not specifically
call out two parts.

Use `Array<T | U>` when dealing with union types instead of  `(T | U)[]`

We compile using the alwaysStrict flag so these directives are not needed

fixes #57789