add flags for headscale serve to provide initial api key

[GrigoriyMikhalkin]

Just played around to check one of the possible solutions to https://github.com/juanfont/headscale/issues/662.

Here i introduced 3 new flags for headscale serve command: api-key-prefix, api-key-pass and api-key-expiration. Together they allow to save pre-generated API key into DB to use it later for authentication.

[GrigoriyMikhalkin]

Another, probably better, idea is to introduce new command: headscale apikeys save --prefix<> --password<> --expiration<>. That would be more flexible.

[juanfont]

Another, probably better, idea is to introduce new command: headscale apikeys save --prefix<> --password<> --expiration<>. That would be more flexible.

I agree. I think the place to create predefined api keys is in the apikeys subcommand. serve is... well... to serve the server.

[kradalby]

I dont think we should implement this, comment in the issue.

[juanfont]

Going to close this one, as we need to rethink a bit how to do it.