refactor bmi adapters into their own library #1630

Job	Run time
test_bmi_cpp (ubuntu-latest)	1m 58s
test_mpi_remote_nexus (ubuntu-latest)	1m 19s
test_pet (ubuntu-latest)	2m 1s
test_bmi_cpp (macos-latest)	3m 20s
test_unit (ubuntu-latest)	2m 1s
test_pet (macos-latest)	3m 39s
test_unit (macos-latest)	3m 23s
test_bmi_c (ubuntu-latest)	1m 58s
test_bmi_fortran (ubuntu-latest)	2m 24s
test_bmi_multi (ubuntu-latest)	2m 33s
test_bmi_c (macos-latest)	4m 16s
test_bmi_multi (macos-latest)	4m 3s
test_bmi_fortran (macos-latest)	3m 46s
test_bmi_python (ubuntu-latest)	2m 7s
test_bmi_python (macos-latest)	4m 28s
	43m 16s

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