Support headscale

[joryirving]

Is your feature request related to a problem? Please describe.
There's currently an option to add tailscale, but unfortunately this doesn't apply. It has the box to override the URL, which is great, but when I try to add my API key for my headscale instance, I get an error stating `failed after 3 retries: invalid API key format. Must start with 'tskey-api-', which my headscale API key does not start with.

Describe the solution you'd like
I'd like to support headscale.

Describe alternatives you've considered
N/A

Additional context
N/A