Prevent automatic assignment of hotkeys to passive mutations

[kightlygeorge]

Summary

Interface "Prevent automatically assigning keys to passive mutations"

Purpose of change

Stops passive mutations from being assigned characters. I've already done this with bionics, but I forgot that mutations did this too.

Describe the solution

During invlet assignment, check if the mutation is active before assigning an invlet

Testing

Created a new character with several passive and active mutations. Only active mutations had hotkeys.

Additional context

Mutation hotkeys are assigned every time the mutations menu is opened instead of being persistent for some reason.