[ENH] - Allow configuring jupyter_server_config.py and overrides.json from config file

[krassowski]

Feature description

Currently only a few options in jupyter_server_config.py can be configured from the config file. No overrides options can be configured from the config file. This severely restricts Jupyter configuration.

Value and/or benefit

• More configuration options

Anything else?

No response

[krassowski]

Thinking more on this, there is a different level of trust to the operator with respect to allowing full configuration of jupyter_server_config vs overrides. overrides mostly pertain the user UI and flipping them is unlikely to ever lead to a major breakage. On the other hand, flipping some settings in jupyter_server_config can lead to unintended or dangerous consequences and here having an allow-list of settings that operators can change might be desirable.