[clang] [CIR] Support zero-result ops in clangir TableGen lowering (PR #202273)

[Jiahao Guo via cfe-commits]

E00N777 wrote:

I have some questions and would like some advice:
Should I change all zero-result ops in this PR to use tablegen to generate lowering logic?
How should I reserve for the case of multiple results?

https://github.com/llvm/llvm-project/pull/202273