[MemProf] Support cold-only and min hint when optimizing existing hot/cold new (#218803)
Change -optimize-existing-hot-cold-new to an enum option supporting:
- none (default): Do not optimize existing hot/cold new calls
- cold: Only optimize existing hot/cold new calls if determined to be
cold
- always: Always optimize existing hot/cold new calls
Add a new option -min-existing-hot-cold-new-hint (off by default) that,
when optimizing an existing hot/cold operator new call, takes the
minimum
of the compiler hint and the existing hint.