Temporarily Revert "[Dsymutil][Debuginfo][NFC] Refactor dsymutil to separate...

Temporarily Revert "[Dsymutil][Debuginfo][NFC] Refactor dsymutil to separate DWARF optimizing part 2."
as it causes a layering violation/dependency cycle:

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp -> llvm/DebugInfo/DWARF/DWARFExpression.h
llvm/include/llvm/DebugInfo/DWARF/DWARFOptimizer.h -> llvm/CodeGen/NonRelocatableStringpool.h

This reverts commit abc7f680.