[clangd] consider ~^foo() to target the destructor, not the type

This behavior was once deliberate, but i've yet to find someone who likes it.
The reference behavior is unchanged: the `foo` within ~foo is still considered
a reference to the type. This means rename etc still works.

fixes https://github.com/clangd/clangd/issues/179

Differential Revision: https://reviews.llvm.org/D136212