I have made a repository with all the packages at one place which makes it comparatively simple to install PR2_moveit.
Here is the link - https://github.com/addy1997/pr2_ROS.git
The classical mechanism to collect repositories like this is using wstool (or, nowadays, vcs) to create a yaml file that contains all information on the repositories.
Also, I have no idea how you managed to do it, but the submodules you added in your linked repository do not have urls associated.
I have made a repository with all the packages at one place which makes it comparatively simple to install PR2_moveit. Here is the link - https://github.com/addy1997/pr2_ROS.git