Centralize dynamic config

[Sushisource]

What was changed

Read dynamic config from a central location

Why?

Makes it easier for users of the repo in full-on environments like k8s have a file they can just grab and use for server dynamic config.

Checklist

1. Closes Centralize dynamic config #529

2. How was this tested:
   Existing features work that need these features enabled

3. Any docs updates needed?

[cretz]

Note, one of the reasons we called it --dynamic-config-value on the CLI was with the expectation there may be a --dynamic-config-file in the future. Would support adding that now if anyone has the time/desire.

[Sushisource]

Note, one of the reasons we called it --dynamic-config-value on the CLI was with the expectation there may be a --dynamic-config-file in the future. Would support adding that now if anyone has the time/desire.

It requires changes to the server library itself to support stuff properly. Namely, merging of file-based and explicitly passed properties.