[Feature] multiple replicas of headscale instances

Use case

currently, there is no option for running headscale in a high availability way. if one goes down, the whole tailnet is unreachable.

Description

adding an option for using multiple headscale servers to distribute the load as well as making sure every server syncs the config so the tailnet is highly available. are there any plans for such a feature?

Contribution

• I can write the design doc for this feature
• I can contribute this feature

How can it be implemented?

No response