[Feature Request] Escalator auto reload configuration on change

**Is your feature request related to a problem? Please describe.**

Updating escalator config currently requires a pod restart. We should update escalator to automatically read new config upon changing on disk.

**Describe the solution you'd like**

Check for changes in nodegroup config before each run. If safe to do so, run with the new config.

**Describe alternatives you've considered**

- Dynamically reading config from a NodeGroup CRD
- Not auto updating config

**Additional context**

This is useful for updates of escalator config without needing manual pod rotation.

Start by locating where Escalator loads its nodegroup configuration and where each run begins. Check how configuration changes on disk can be detected before a run, then verify that a safe updated configuration is used without restarting the pod; the existing behavior and relevant tests will show the completion criteria.

Written by the indexing model from the issue text.