This implements `hover`, `pointer`, `any-hover` and `any-pointer` and
the values `course`/`fine` (pointer) and `hover`.
A best effort is made to get capabilities from the system but if unknown
always falls back to assuming a mouse is present.
- Remove numerous blocklist entries that no longer apply.
- Remove CanComputeVirtualKeyCodeFromScanCode(), because it's always true.
- Remove ShowXP{Folder,File}Picker(), since we have native pickers on supported Windows versions.
- Remove the config.trim_on_minimize preference, which is pointless on NT6+ and will just cause problems if used.
Tag #22.