[clang] [CIR] Use SymbolTableCollection in LoweringPrepare's getCalledFunction (PR #195919)

[Erich Keane via cfe-commits]

erichkeane wrote:

> Cannot we just use `mlir::SymbolTAbleAnalysis` attached to top-level module op, and pick symboltablecallection from it? one does not need to polute API with passing tables everywhere I guess, and hopefully we can reuse analysis accross passes not to compute SymbolTAble for each pass again?
> 
> See: https://mlir.llvm.org/doxygen/classmlir_1_1SymbolTableAnalysis.html for reference. Also might be interresting to measure if we create one global analysis whether the numbers get even lower.

I was going to suggest we stop threading this through.  It is like it is, as this is how you suggested it on my initial patch, but the more I work wiht this, the more I suspect we should have SOME sort of member.  

it isn't clear to me the value of `SymbolTableAnalysis` vs just storing a collection though.

https://github.com/llvm/llvm-project/pull/195919