Add update_repositories script to simulacrum for docker

[MattKing06]

If users are not building the docker container on they're local machine and are instead pulling from dockerhub then they will have fixed versions of the dependency repos (LCLS-tools, LCLS-lattice, etc.)

To ensure that these repositories can be updated for any static docker image, a script can be added that pulls the main branches of the repos and reinstalls them to local python packages in the docker container.

This issue is part of a wider fix which will allow automated building and pushing of the simulacrum docker image using Github Actions.