Migrate `rvalue` and `coercion` module to use StableMIR #5932

Job	Run time
regression (macos-12)	40m 11s
regression (ubuntu-20.04)	20m 3s
regression (ubuntu-22.04)	21m 53s
benchcomp-tests	3m 40s
bookrunner	16m 38s
perf	26m 41s
write-json-symtab-regression	11m 46s
	2h 20m 52s

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