[ENH] - Allow configuration of custom services in jhub apps #3164

Feature description

Essentially what is described in nebari-dev/jhub-apps#626

We are close to being able to configure MLflow in the "Quick Access" and "Services" sections of Jhub Apps. We need

• review/merge of Pinned services via JAppsConfig jhub-apps#636
• build new jupyterhub image
• deploy nebari from this branch - update for latest jhub apps #3163
• add new image to nebari-config to this PR and merge - https://github.com/openteams-ai/nebari-deployment/pull/5/files

Value and/or benefit

extensibility

Anything else?

No response