[AST] Correct the CXXOperatorCallExpr source range.

Summary:
Previously, the range for "->" CXXOperatorCallExpr is the range of the
class object (not including the operator!), e.g. "[[vector_ptr]]->size()".

This patch includes the range of the operator, which fixes the issue
where clangd doesn't go to the overloaded operator "->" definition.

Reviewers: sammccall

Reviewed By: sammccall

Subscribers: ilya-biryukov, jkorous, arphaman, kadircet, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D76128