Extend comparison lifting to `Core.ifelse` (#49882)
This change extends our existing transformation for:
φ(a,b) === Const(c) => φ(a === c, b === c)
to perform the analogous transformation for `Core.ifelse`:
Core.ifelse(cond, a, b) === Const(c)
=>
Core.ifelse(cond, a === c, b === c)
