Removing a mount should stop any services created by that mount

[kdmccormick]

Background

Example:

tutor mounts add path/to/frontend-app-course-authoring
tutor images build  # builds a new image: course-authoring-dev
tutor dev start -d  # starts a new service: course-authoring

tutor mounts remove path/to/frontend-app-course-authoring
tutor dev stop      # course-authoring isn't stopped!

tutor mounts add path/to/frontend-app-course-authoring
tutor dev stop      # NOW course-authoring is stopped
tutor mounts remove path/to/frontend-app-course-authoring

### Tasks

TBD

### Notes

_No response_