Migrate `rvalue` and `coercion` module to use StableMIR #5933

Job	Run time
benchcomp-tests	4m 22s
bookrunner	17m 12s
perf	26m 41s
regression (macos-12)	30m 17s
regression (ubuntu-20.04)	19m 20s
write-json-symtab-regression	10m 55s
regression (ubuntu-22.04)	22m 17s
	2h 11m 4s

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