[Feature] Ability to test machine learning server URL reachability

[TheDidek]

I have searched the existing feature requests to make sure this is not a duplicate request.

• Yes

The feature

Ref to: https://immich.app/docs/guides/remote-machine-learning

Immich settings interface does not let user check if the typed URL is actually reachable, making it hard to see mistake when using more complex network setups.

Platform

• Server
• Web
• Mobile

[Kieranwest]

This would be great.