[clang] [CIR] vTableClassNameForType: return correct VTableClass name for Type::ObjCObjectPointer, Type::Pointer (PR #163850)

[via cfe-commits]

n2h9 wrote:

> Might be worth moving this out of draft if you want more visibility

We have figured out that there is a blocking code which is not yet implemented in [CIRGenItaniumRTTIBuilder::buildTypeInfo](https://github.com/llvm/llvm-project/blob/main/clang/lib/CIR/CodeGen/CIRGenItaniumCXXABI.cpp#L1416). 
More details in this [comment](https://github.com/llvm/llvm-project/issues/163601#issuecomment-3419652116).
So keeping this as draft for now, until the code will be added :innocent: . 

https://github.com/llvm/llvm-project/pull/163850