CI: run the pytao test suite with every bmad commit

[ken-lauer]

Changes

• Added a pytao continuous integration test workflow
  • It builds and tests the latest bmad with the latest pytao master
  • It only runs Python 3.12 with shared libraries and MPI off
• Added pytao-focused conda-setup action
• Moved dependency setup to its own composite action, so it could be shared with the pytao workflow
• Adjusted install_bmad.sh to use nproc instead of just hard-coding 2.
  • GitHub actions workers have 4 vCPUs - which resulted in a few minutes shaved off the bmad build in my limited testing.
• Adjust the test suite workflow to build on every commit
  • It's common for collaborators to make feature branches, so it would be nice if forks would run the test suite by default as well

Since it builds bmad and then runs the 600ish tests bundled with pytao, it ends up taking a rather long time (~35 minutes).

Future possibilities

• The pytao installation could be used to run additional integration tests. In my opinion:
  • Data files should continue to live in bmad-doc/tao_examples (or regression_tests depending on the purpose)
  • The pytest test suites that utilize those data files should live in the pytao repository
• This could potentially be changed at some point to reuse the build from the primary bmad build/test suite (i.e., the ci.yml job) down the line, but I don't have the time for it right now.

[DavidSagan]

@ken-lauer Just so there is clarity: I am waiting for you to indicate that everything is ready for me to look at.

[ken-lauer]

@DavidSagan - it will take some time to reduce the test suite duration to a level that's acceptable for your development practices. I'll mark this as draft until I can make some progress in the above-linked PR.