[DWARF] Translate this in a more accessible way

[SingleAccretion]

Currently, for instance methods, this pointers are translated like all other pointers - wrapped in the synthetic types. However, this breaks LLDB's ability to do anything with them as it expects this to be a proper pointer.

(There are still ways to inspect the underlying data, of course, but they're more clunky than just p Member.)

The proposed fix, consistent with the existing system, would be to rename this and effectively transform all instance methods into static ones.

The user experience would then be p __this->Member instead of p Member.

A more ambitious alternative is to translate it into a proper pointer. Unlike for a number of other cases, we can do that (since we have the frame context available), but it's a bit more complicated (need to intelligently intersect ranges of __vmctx with those of this) and more importantly, it wouldn't be consistent with how the rest of the system operates.