Deliver wifi/bluetooth firmware via systemd-sysext

[lauretano]

Combine the asahi/t2linux radio firmware script's ability to download and tar up the official recovery image firmware with a script to create and install a systemd-sysext to drop the firmware in /usr/lib/firmware. Deal with selinux as necessary.

Ideally this would support a user supplied firmware.tar or firmare.rpm but not strictly necessary to get started.

[lauretano]

Initial local testing of this with a local firmware.tar resulted in a lot of selinux errors from NetworkManager attempting to access the /usr/lib/firmware path. Seems like some labeling gets screwed up when the sysext is merged (active).