De-duplicate edges in `typeinfer` instead of `gf.c` (#58117)
Without this PR, my system spends ~1.07 seconds just running
`store_backedges` when doing `using CairoMakie`
With this change, that drops to `0.641 seconds`
That's still not fast enough for me, but we do call this function
236,092 times so maybe it's understandable.
