adds Berkeley UCB source time function feature #210

Job	Run time
Check file changes	20s
Test on ubuntu-latest	2m 41s
Test Intel on ubuntu-22.04	11m 21s
Test on ubuntu-22.04	2m 39s
Test on Mac	7m 32s
Test run example 1 - regional_Greece_small debug	2m 33s
Test run example 10 - regional_Greece_small_LDDRK kernel ADIOS2	10m 40s
Test run example 0 - make tests	10m 25s
Test run example 2 - regional_Greece_small	3m 51s
Test run example 3 - regional_sgloberani	3m 39s
Test run example 4 - point_force	4m 28s
Test run example 5 - moon_global	5m 39s
Test run example 6 - mars_regional	3m 18s
Test run example 7 - global_small	4m 55s
Test run example 8 - global_small w/ FULL_GRAVITY netCDF	10m 37s
Test run example 9 - global_small w/ FULL_GRAVITY PETSc	5m 35s
	1h 30m 13s

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