Speed up Docker build

[paulromano]

Description

This PR makes a few updates to our Dockerfile to speed up build times:

• Instead of building Embree from source it uses the apt package
• Similarly, pugixml and libfmt are installed from apt
• Avoids building tests for MOAB and DAGMC

The Embree change alone should shave off 15-20 min of build time.

Checklist

• I have performed a self-review of my own code
• I have run clang-format (version 15) on any C++ source files (if applicable)
• I have followed the style guidelines for Python source files (if applicable)
• I have made corresponding changes to the documentation (if applicable)
• I have added tests that prove my fix is effective or that my feature works (if applicable)

[GuySten]

If we use fmt and pugixml from apt, we should not include them as submodules.

[paulromano]

We include the submodules as a backup so that people are not required to have them installed already. However, if they do have them installed and find_package finds them, the submodules don't get built.