[clang] [CIR] Upstream __imag__ for ComplexType (PR #144262)

[Amr Hesham via cfe-commits]

AmrDeveloper wrote:

I updated the error message; previously, the op name was printed twice

`unexpected error: 'cir.complex.real' op cir.complex.real result type does not match operand type`

Now

`unexpected error: 'cir.complex.real' op : result type does not match operand type`

https://github.com/llvm/llvm-project/pull/144262