Push ash worker user down the service

Is your feature request related to a problem? Please describe.
Currently if service (that is being triggered by Ash) is running as root (unless user is created - hardcoded- in service Dockerfile).

This could cause an permission issue in services that are using mounted volumes. (Eg. service is mounting studio drive where it publishes, published files from that service have user 'root' which could be troublesome.)

Describe the solution you'd like
It could be beneficial to have toggle that would control if underlaying service should be inheriting user that Ash worker is running. That way studios could easily control permissions by just changing who is running Ash service.

Another option would be providing field/env var that could be used to provide different user name (that is existing on an environment that ash worker is running.)

Additional context
It looks that orchestrators could control users that are running their started service by --user flag. I am not sure if it is really the case. My described solution comes from this notion.

Start by tracing how Ash launches the underlying service and how the service Dockerfile and orchestrator invocation handle the user. Compare the proposed inherited-user toggle with an explicit user name or environment setting, including the --user behavior mentioned in the issue. Done means one supported, documented way to control the service user and verified permissions for mounted volumes.