api: Allow unauthenticated access to user's SSH keys

[wiktor-k]

This patch relaxes constraints on getting user's SSH keys via the JSON API. The same has been allowed by both GitHub and Gitlab and the output is already readable via http://domain/user.keys endpoint.

The benefit of allowing it via the API are twofold: first this is a structured output and second it can be CORS-enabled.

As a privacy precaution the Title property is set to an empty string if the request is unauthenticated.

Fixes: #30681

[lunny]

I think we should just expose the id and key like what Github did. i.e. https://api.github.com/users/lunny/keys

[wiktor-k]

I think we should just expose the id and key like what Github did. i.e. https://api.github.com/users/lunny/keys

There's a slight problem that the time cannot be nil'd. Although I found a way by using *time.Time I'm not sure if that's the way to follow (because it'd change the API). (I'm no go developer so excuse my basic questions).

Just for the record the API for returning "signing SSH keys" does include creation time and title: https://api.github.com/users/wiktor-k/ssh_signing_keys

[lunny]

If you don't mind, I can send some commits to your PR.

[wiktor-k]

If you don't mind, I can send some commits to your PR.

I would be very glad if you could help 🙏 thank you in advance! 🙇