Operator splitting, adaptive time stepping, and other fixes for mixing layer and bubbles #219

Job	Run time
Github \| Docker	59m 33s
Github (ubuntu, mpi, debug, true)	23m 30s
Georgia Tech \| Phoenix (NVHPC) (cpu)	46m 6s
Github (ubuntu, mpi, debug, false)	50m 39s
Georgia Tech \| Phoenix (NVHPC) (gpu)	31m 17s
Github (ubuntu, mpi, no-debug, true)	1h 2m 20s
Github (ubuntu, mpi, no-debug, false)	59m 4s
Github (ubuntu, no-mpi, debug, true)	17m 55s
Github (ubuntu, no-mpi, debug, false)	24m 9s
Github (ubuntu, no-mpi, no-debug, true)	36m 58s
Github (ubuntu, no-mpi, no-debug, false)	19m 5s
Github (macos, mpi, debug, false)	56m 30s
Github (macos, mpi, no-debug, false)	1h 21m 41s
Github (macos, no-mpi, debug, false)	23m 0s
Github (macos, no-mpi, no-debug, false)	39m 24s
	10h 31m 11s

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