Run benchmarks weekly in CI

[chapman39]

This PR...

• Adds run_benchmarks.py script that builds Serac, runs benchmarks, and moves resulting Caliper files in shared location on LC.
• Sets up CI such that this script is run on all platforms (ruby, lassen, tioga)
• Setup weekly Pipeline Schedule on Gitlab

Also,

• Disables benchmarks on full builds (since benchmarks are being compiled on src already)
• Fixes cray full CI builds? (it was not using the spec in specs.json)
• Fixes physics_benchmark_solid_nonlinear_solve benchmark to handle petsc being disabled

[chapman39]

We could alternatively use some sort of CI_WORKFLOW_TYPE var which could be src, full, or benchmarks. That way we don't have to handle the two variables. I just don't have access to nightly build settings.