Feature/mrhs prep part deux

[maddyscientist]

This PR continues the multi-RHS scaffolding from #1437:

• All BLAS functions are now multi-RHS aware (albeit for-loop wrappers around single RHS operations)
  • (Future work will fuse these into single kernels)
• BLAS regression tests are much more robust with most of the tests now tested using elementary equivalent compositions, as opposed to simply comparing CPU and GPU
• Block BLAS functions are now in their own namespace blas::block to avoid any collisions with the new multi-RHS aware BLAS functions
• Legacy block BLAS functions (those that take a vector of pointers) are now in the blas::legacy namespace.
  • Hopefully these will be deleted soon
• Dirac::prepare and Dirac::reconstruct functions are now multi-RHS aware
• General clean up of the Dirac classes to reduce boiler plate

[weinbe2]

Waiting on clang-format to actually merge