refactor!: move preconditioners inside linear solvers (#485) #134

Job	Run time
test (1.10, ubuntu-latest, core)	13m 11s
test (1.10, ubuntu-latest, adjoint)	8m 25s
test (1.10, ubuntu-latest, alloc_check)	8m 34s
test (1.10, macos-latest, core)	12m 55s
test (1.10, macos-latest, adjoint)	5m 48s
test (1.10, macos-latest, alloc_check)	7m 17s
test (1.10, windows-latest, core)	14m 46s
test (1.10, windows-latest, adjoint)	10m 29s
test (1.10, windows-latest, alloc_check)	10m 22s
test (1, ubuntu-latest, core)	21m 27s
test (1, ubuntu-latest, adjoint)	15m 43s
test (1, ubuntu-latest, alloc_check)	14m 27s
test (1, macos-latest, core)	16m 1s
test (1, macos-latest, adjoint)	11m 6s
test (1, macos-latest, alloc_check)	11m 6s
test (1, windows-latest, core)	23m 33s
downgrade (1.10, core)	13m 16s
downgrade (1.10, adjoint)	8m 29s
test (1, windows-latest, adjoint)	17m 32s
downgrade (1.10, alloc_check)	8m 33s
test (1, windows-latest, alloc_check)	16m 25s
	4h 29m 25s

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