install: Allow focus ajustment on Librem 5
Focus is controlled using a command gated by sudo, and sudo requires a password now. This is a hack to enable passwordless sudo for the single command, to be maintained until the camera interface itself gains the ability to control focus.
This is @dorota.czaplejewicz's https://source.puri.sm/Librem5/megapixels/-/merge_requests/49 brought over verbatim to pureos/byzantium.