Docker: Automatically create missing user accounts in the entrypoint-init.sh script

[lastzero]

As a user running PhotoPrism under an unusual user ID, I want the Docker image to automatically create a user account on startup, as required by the /usr/bin/setpriv command that's used to start the service under a non-root user ID.

[lastzero]

An updated photoprism/photoprism:test image including these changes should be available on Docker Hub within the next two hours:

• https://hub.docker.com/r/photoprism/photoprism/tags?page=1&name=test

We appreciate your feedback and help with testing! 🙏

[lastzero]

You can now test this by changing the photoprism/photoprism image tag in your docker-compose.yml from :latest to :test and then run the following commands to download the most recent image and restart your instance in the background:

docker compose pull
docker compose stop
docker compose up -d

The following docs provide additional help for updating your instance:

• https://docs.photoprism.app/getting-started/updates/