Create template repo for Kuberhealthy checks

[jonwinton]

Context: the main Kuberhealthy repo currently deploys the default Checks under the same tags as the primary controller. We'd like to separate Checks from the primary controller so that each Check and the controller can iterate separately.

This task is to make GitHub Template Repository to make creating future Checks easy.

The template repo should come with some same defaults, such as:

• A script for end-to-end testing in a GitHub Action
• Basic validation tooling
• Dependency updating tooling (i.e., Renovate)
• Image building/releasing tooling