feat: use specialization in NonlinearProblems #149

Job	Run time
Tests (1, Downstream2) / Tests - Downstream2	16m 51s
Tests (1, Core) / Tests - Core	4m 26s
Tests (1, Downstream) / Tests - Downstream	10m 43s
Tests (lts, Core) / Tests - Core	6m 18s
Tests (lts, Downstream2) / Tests - Downstream2	14m 16s
Tests (lts, Downstream) / Tests - Downstream	6m 38s
Tests (pre, Core) / Tests - Core	6m 48s
Tests (pre, Downstream) / Tests - Downstream	10m 42s
Tests (pre, Downstream2) / Tests - Downstream2	19m 13s
	1h 35m 55s

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