[DomTreeUpdater] Move critical edge splitting code to updater (#115111)
Support critical edge splitting in dominator tree updater. Continue the
work in #100856.
Compile time check:
https://llvm-compile-time-tracker.com/compare.php?from=87c35d782795b54911b3e3a91a5b738d4d870e55&to=42b3e5623a9ab4c3648564dc0926b36f3b438a3a&stat=instructions%3Au