fix(windows): Some registry keys could have incorrect permissions

Fixes #3665.

On some systems, subkeys of HKCU\Software\Keyman could have incorrect
permissions and these would not be corrected with earlier fixes such as
in #2316. This fix resolves the problem by recursively correcting
permissions on all subkeys, rather than just the top two levels.

This issue caused Metro-style applications (Windows Store apps) to fail
to accept Keyman keyboard input.