Staggered invert test cleanup + expanded staggered gtest support

[weinbe2]

This PR is a massive cleanup and refactor of various staggered test executables: staggered_dslash_(c)test, staggered_invert_test, staggered_eigensolve_test, and hisq_stencil_test. Motivators:

• Homogenize these different tests as much as possible (as is appropriate)
• Include gtest support in all of them
• Make the tests as stylistically similar to the Wilson versions (dslash_(c)test, invert_test, and eigensolve_test) as possible
• Add support for testing the Laplace operator when it is enabled at compile time (-DQUDA_LAPLACE)

Some cleanup happened along the way:

• BiCGStab cleanup:
  1. Switching it to explicitly use ColorSpinorField objects as opposed to pointers thereof
  2. More robustly improve the final convergence (in some cases the final solution may have been slightly above the tolerance, i.e., ~1.01e-6 when the requested tolerance was 1e-6). The addition of staggered_invert_test ctests uncovered this!
• Move some of the is_[...]_[solve/solution/etc] routines out of the invert test helpers and into the more general host_utils files.

A few gotchas of note:

• The default behavior of staggered_invert_test is now to solve the preconditioned operator with conjugate gradient, since that's arguably the most typical use case. The previous default was solving the full operator with bicgstab.
• I removed the --test [#] flags from staggered_invert_test to more closely match the behavior of invert_test. I created a new flag --legacy-test-info that will print the appropriate command line arguments to reproduce each old test.

I did make a few changes in preparation of adding support for the "local" staggered operators, which can be used for Schwarz preconditioning. This includes copying and pasting some relevant bits of code from Wilson-type files into the staggered-type files, commenting the code out, and explicitly leaving an additional comment that this is for future reference. I know this is generally not a best practice, but hopefully it's understandable in this case.

As it stands, a staggered-only build does indeed pass ctest -v.

There are some small bits of outstanding work, but nothing I see as holding up PR review right now. They are:

• [x] Confirming ctest -v for Wilson-type fermions still works (this PR nearly exclusively effects staggered tests, but I did introduce a few abstractions that maybe went awry for Wilson)
• [x] Formally confirming deflation still works in staggered_invert_test
• [x] Formally confirming MG still works in staggered_invert_test
• [x] Checking workflows that use bicgstab
• [x] doxygen
• [x] clang-format

[weinbe2]

• Staggered eigensolves take much longer than their Wilson brethren. Anything to be done here?
• HISQ stencil test looks like it's taking longer than expected: is there unnecessary setup being redone between partitions?

Based on offline conversations, the time spent on staggered eigensolves has been addressed in https://github.com/lattice/quda/pull/1421/commits/a1303bd612cf8dfaf5b7a7070cd5871ad4b6b5ce , plus some additional opportunities to speed up the unit tests run on CSCS in https://github.com/lattice/quda/pull/1421/commits/3252b6cdf1c1e66a27ce27677e9b776014e15190 . The HISQ stencil test time was decided to be reasonable.

[weinbe2]

~@maddyscientist this should be good for a last review + clang-format~

Got a few things to fix in BiCGstab with regards to MG (near-null vector generation and pre-smoothing)