Add key expiry disable/enable toggle

[jul13579]

This PR adds a button to the node menu to disable (and re-enable) node key expiry, as requested by #553. Since headscale does not store the key expiry toggle state separately from the actual expiry date, re-enabling key expiry sadly currently will result in a node that expired at the time of re-enabling the key expiry. This is not the case with official tailscale, which seems to pick up the original key expiry date from before key expiry was disabled. Hence, I'm actually unsure myself if this feature adds much to the UX of headplane 🤷

[tale]

This fails integration testing and I'd also hold off as I'm changing things somewhat significantly.

[jul13579]

This fails integration testing and I'd also hold off as I'm changing things somewhat significantly.

I'm not entirely sure since I haven't looked that much into it, but I believe the tests are failing since the CI is using the latest release version of headscale. The PR adding this headscale feature however hasn't actually made it into a release version yet..

If you don't mind, I'll keep the PR update as best as I can. The changes are few enough for me to adapt them to the changes happening upstream.

[jul13579]

@tale This PR now passes integration tests for headscale versions 0.29.0+. Please tell me if you'd like anything changed about the implementation, such that it meets your requirements for integration 😉