[lldb] Preserve type sugar when using SBValue::Dereference on C++ references

When checking for type properties we usually want to strip all kind of type
sugar from the type. For example, sugar like Clang's ElaboratedType or typedefs
rarely influence the fundamental behaviour of a type such as its byte size.

However we always need to preserve type sugar for everything else as it does
matter for users that their variable of type `size_t` instead of `unsigned long`
for example.

This patch fixes one such bug when trying to use the SBValue API to dereference
a type.

Reviewed By: werat, shafik

Differential Revision: https://reviews.llvm.org/D103532