Chase mixer(8) command-line interface changes

FreeBSD 14.0 is going to ship with a new implementation of the mixer(8)
command. Unfortunately, in order to support new features like mute, the
command-line interface of the new implementation is not backwards
compatible.

Update all the remaining documentation and scripts in the src tree
to use the new syntax.

While here, document in usbhidaction.1 that the mute functionality is
now supported.

Reviewed by: christos, debdrup, hselasky
Approved by: hselasky (src)
Fixes: 903873ce1560 Implement and use new mixer(3) library for FreeBSD.
Differential Revision: https://reviews.freebsd.org/D34545