[IR] Sink `isExceptional` predicate to `Instruction`, rename it to
`isExceptionalTermiantor` and implement it for opcodes as well following
the common pattern in `Instruction`.

Part of removing `TerminatorInst` from the `Instruction` type hierarchy
to make it easier to share logic and interfaces between instructions
that are both terminators and not terminators.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@340699 91177308-0d34-0410-b5e6-96231b3b80d8
10 files changed