[CIR][CodeGen] Missing catch-by-reference implementation

[tommymcm]

Minimized test case:

#include <ios>
class A {};
A B(A A) try { B(A); } catch (std::ios &) {
}

Failed assertion:

clangir/clang/lib/CIR/CodeGen/CIRGenItaniumCXXABI.cpp

Line 764 in aeac352

llvm_unreachable("NYI");

Flags: -fclangir -O2