[SelectionDAG] Add space-optimized forms of OPC_CheckPatternPredicate (#73319)

We record the usage of each `PatternPredicate` and sort them by
usage.

For the top 8 `PatternPredicate`s, we will emit a
`OPC_CheckPatternPredicateN` to save one byte.

The old `OPC_CheckPatternPredicate2` is renamed to
`OPC_CheckPatternPredicateTwoByte`.

Overall this reduces the llc binary size with all in-tree targets by
about 93K.