chore(windows): merge vkeys.h and move to common

Moves vkeys.h to common, turns it into a proper header and adds
corresponding vkeys.cpp so that we don't include the data multiple times
in a project.

Removes duplication of vkeys.h in kmcmpdll and global/inc.

Updates all projects to reference the common files, except kmdecomp,
coming in the next commit, as it is more complex.