Health check to restart the keyper in case of keyper hangs

[ylembachar]

We should add a Docker health check to detect cases where the keyper is hanging.

Goal

• Automatically detect when the Keyper is hanging
• Let Docker restart the container when the health check fails.
• Log restart events so we can see them in metrics

Proposed approach

• Add a health check in Dockerfile
• When the health check fails 3 times in a row, Docker marks the container as unhealthy and restarts it.

Additional information:
Instead of the ping endpoint that relies on user input, rather use a new endpoint that is not reliant on user specific configuration, but that is still configurable internally, i.e. make it a regular option in the keyper config, but don't expose it in the docker env var based setup but just set it to enabled in the config script.