Various improvements to Clang MSVC Visualizer

This change adds/improves MSVC visualizers for many Clang types, including array types, trailing return types in function, deduction guides, a fix for OpaquePtr, etc. It also replaces all of the view(deref) with the "na" formatter, which is a better built-in natvis technique for doing the same thing. 

Differential Revision: https://reviews.llvm.org/D63039

llvm-svn: 363574