[2.x] Add sanctum:prune-expired command for removing expired tokens.

[yuraplohov]

This command has long been needed by developers.
A similar command is present in Telescope and Passport packages.

[ankurk91]

The command does not return any thing.
The exit codes must be added

[driesvints]

Thanks @ankurk91. I sent in a PR for that: #351

[EdgarSedov]

@yuraplohov @ankurk91 @driesvints
Hey guys, thanks for awesome command, it's good that we don't need to write it ourselves.

I have one question - is there any special reason why we use created_at instead of last_used_at as where condition for pruning?

[yuraplohov]

Thank you, @EdgarSedov

I used created_at in this logic, because expiration of token in Sanctum based on created_at exactly. Maybe, expiration by last_used_at is needed in this package, but that's another question. I saw PR #349 with similar idea recently.