mir: use `Local` instead of `PSym` for locals #5127

Job	Run time
Provide additional context for the workflow	6s
Build release binaries (Linux)	7m 6s
Build release binaries (macOS)	4m 59s
Build release binaries (macOS (M1))	2m 54s
Build release binaries (Windows)	12m 27s
Build source archive	2m 45s
Build and test tooling (Linux)	2m 46s
Build docs and release artifacts (Linux)	7m 15s
Build and test tooling (macOS)	4m 35s
Test the compiler and stdlib (Linux, batch #0)	5m 40s
Build docs and release artifacts (macOS)	6m 22s
Build and test tooling (macOS (M1))	1m 54s
Test the compiler and stdlib (Linux, batch #1)	5m 21s
Build docs and release artifacts (macOS (M1))	4m 8s
Build and test tooling (Windows)	3m 25s
Test the compiler and stdlib (macOS, batch #0)	7m 25s
Build docs and release artifacts (Windows)	12m 27s
Test the compiler and stdlib (macOS, batch #1)	6m 0s
Test the compiler and stdlib (macOS (M1), batch #0)	3m 39s
Test the compiler and stdlib (macOS (M1), batch #1)	3m 57s
Test the compiler and stdlib (Windows, batch #0)	10m 9s
Test the compiler and stdlib (Windows, batch #1)	11m 17s
Build release artifacts from source archive (Linux)	9m 59s
Build release artifacts from source archive (macOS)	18m 58s
Build release artifacts from source archive (macOS (M1))	4m 55s
Build release artifacts from source archive (Windows)	18m 29s
Test release artifacts	56s
All check passed	1s
	2h 59m 55s

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