[llvm] [GlobalISel] Introduce G_TRAP, G_DEBUGTRAP, G_UBSANTRAP (PR #84941)

[Evgenii Kudriashov via llvm-commits]

e-kud wrote:

> Can you put this in the PR description so it will end up in the commit message.

@topperc I've rephrased in more general terms. 

I've noticed that there are checks for GMIR opcodes in MachineVerifier. Should I add sanity checks that `G_TRAP` and `G_DEBUGTRAP` have no args and `G_UBSANTRAP` has only an `i8` immediate argument?

https://github.com/llvm/llvm-project/pull/84941