[clang] [clang codegen] Add CreateRuntimeFunction overload that takes a clang type. (PR #113506)

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

SetLLVMFunctionAttributes() should add the appropriate signext/zeroext attribute.  At least, it appears to work in my testing.  I'll add a regression test.

https://github.com/llvm/llvm-project/pull/113506