[libTooling] Change `access` stencil to recognize use of `operator*`.

Currently, `access` doesn't recognize a dereferenced smart pointer. So,
`access(e, "field")` where `e = *x`, yields:
* `x->field`, for normal-pointer x,
* `(*x).field`, for smart-pointer x.

This patch normalizes handling of smart pointer to match normal pointer, when
the smart pointer type supports `->`.

Differential Revision: https://reviews.llvm.org/D104390