This adds two convenience methods named GetAsLLVM to the LLDB versions of the DWARF DataExtractor and the DWARF context.
Just wondering if we want to cache the llvm::DWARFContext in the LLDB DWARFContext. See inline comments.
Should we cache this lldb's DWARFContext and just hand out a pointer or reference that is owned by this class? Or are we ok creating temp llvm::DWARFContext objects that we will throw away? Is there any state in llvm::DWARFContext that we wouldn't want to re-create or parse is my main concern.