usb-scan->media-scan: usb-init calling media-scan usb

[tlaurion]

media-scan accepts direct input of existing blkid and mount that passed device to /media

[tlaurion]

Hid last comment since it is due to different options being passed.

@JonathonHall-Purism : please review, since present code change works and permits first steps toward booting from already exposed partitions that could have recovery detached signed ISOs which Heads can boot directly.

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The following works:

Recovery shell+ media-scan /dev/sda1

Selecting ISO:

Results in detached signature validation being successful, while current Heads's Tails ditribution public key is expired (fixed by #1094)

Selection External HD:

Boots Tails 5.9 (with

[tlaurion]

Also boots Qubes4.1 successfully, meaning that a user could leave a non-boot partition with enough space to keep detached signed ISOs there, as long as he is aware to pass that partition to media-scan. I think this is neat.

[JonathonHall-Purism]

Looks good, we had a side discussion on possibly factoring out the "how to mount /media" from media-scan but this is a good step. 👍