Add two new APIs for active keyboard layout.

This goes with https://github.com/adobe/brackets/pull/9652.
1. You don't need to mask off the `LOWORD` if you're shifting the value to the right 16 bits.  
1. The `HIWORD` of the return value from `GetKeyboardLayout()`, according to the documentation, is a handle to the physical layout.  That doesn't seem like we should be converting it to a number and using that for a language identifier.