Rework solver chain + small refactoring changes #818

Job	Run time
clang-format	5m 4s
Coverage (STP)	30m 52s
Coverage (Z3)	33m 33s
Docker	11m 22s
Linux (LLVM 14)	13m 39s
Linux (LLVM 13)	20m 35s
Linux (LLVM 12)	14m 33s
Linux (LLVM 11, Doxygen)	15m 4s
Linux (LLVM 10)	13m 59s
Linux (LLVM 9)	12m 34s
Linux (ASan)	35m 9s
Linux (UBSan)	40m 12s
Linux (MSan)	1h 4m 50s
Linux (Z3 only)	19m 25s
Linux (metaSMT)	32m 47s
Linux (STP master)	17m 25s
Linux (Latest klee-uclibc)	15m 17s
Linux (Asserts disabled)	14m 8s
Linux (No TCMalloc, optimised runtime)	13m 17s
macOS	11m 8s
	7h 14m 53s

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