Started implementation of RKAB using CarpetX's timelevels mechanism #1319

Job	Run time
download-build-test (cpu, real32, debug)	11m 34s
download-build-test (cpu, real64, debug)	11m 55s
download-build-test (cpu, real64, optimize)	17m 21s
download-build-test (cuda, real32, debug)	23m 50s
download-build-test (cuda, real64, debug)	24m 20s
download-build-test (cuda, real64, optimize)	22m 56s
download-build-test (rocm, real64, optimize)	19m 52s
	2h 11m 48s

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