Add support for modular build structure. #443

Job	Run time
posix (Collect coverage special_fun, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, special_...	17m 39s
posix (Collect coverage distribution_tests, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, d...	8m 46s
posix (Collect coverage mp, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, mp)	9m 30s
posix (Collect coverage misc, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, misc)	10m 44s
posix (Collect coverage quadrature, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, quadrature)	15m 58s
posix (Collect coverage interpolators, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, interp...	28m 45s
posix (Collect coverage autodiff, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, autodiff)	6m 40s
	1h 38m 2s

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