Support path prefix URLs for frontend and GMS

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

I would like to host the DataHub frontend and GMS with a path prefix, so I may host multiple services with the same DNS name.

Describe the solution you'd like

Allow an optional config url-prefix (or similar name) to be set in Helm/Yaml/Docker-startup/etc. to enable hosting on a path.

This would enable solutions like:
https://my.domain.com/datahub-frontend
and
https://my.domain.com/my-other-app

To more easily coexist on the same k8s cluster.

Describe alternatives you've considered

I have used name-based virtual hosting to route another app with the same challenge by adding a fourth-level domain A record like:
https://my-other-app.my.domain.com

Name-based hosting works, however it requires creating more A records in DNS and our IT group would like to limit how often DNS intervention is required.

Additional context

This scenario was brought up in Slack (ref). In contrast to that conversation, I would suggest both the frontend and GMS support a path prefix.