1.37.28: Redundant Set Elimination pass (#1344)

This optimizes #1343. It looks for stores of a value that is already present in the local, which in particular can remove the initial set to 0 of loops starting at zero, since all locals are initialized to that already. This helps in real-world code, but is not super-common since coalescing means we tend to have assigned something else to it anyhow before we need it to be zero, so this mainly helps in small functions (and running this before coalescing would extend live ranges in potentially bad ways).