Check directory permission in docker-entrypoint.sh with `test -w`

[white-gecko]

Description

I have replaced the individual comparison of the ids with a test -w $VOLUME_DIR resp. ! [ -w $VOLUME_DIR ] check.

Motivation and Context

The comparison of the individual gid and uids of the user and the directory misses out, if the user has permission based on further groups.

Screenshots (if appropriate):

Types of changes

• [ ] Replay fix (fixes a replay specific issue)
• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [ ] I have added or updated tests to cover my changes.
• [ ] All new and existing tests passed. (I hope so)