Allow any key, including Left Alt, as a push-to-talk key

Problem

Currently while trying to set PTT buttons, some keys are unaccepted. One such key is the Left Alt key. For several users I know personally restrictions on PTT keys have been a main sticking point for not fully switching over. If the restrictions on PTT keys could be removed, allowing for any key that would be another reason to make the shift

Proposed solution

Remove restrictions on PTT keys so that any key can be used