fix: support multiple SSHPubKey records per user
There was one blazing issue with the previous implementation regardless of the multiple records: we were generating fingerprints by storing the key into a file and reading it with ssh-keygen. This is absolutely terrible and was not meant to be left around (it was forgotten, my bad).
Took this opportunity to clean up a few things:
- simplify pubkey validation
- centralize things a bit better
Signed-off-by: Kevin Morris kevr@0cost.org