Support dependent name lookup through smart pointers

[Varun Gandhi]

clangd's HeuristicResolver has some code for this. Right now, we don't handle this case.

diff --git a/test/index/functions/templates.cc b/test/index/functions/templates.cc
index 20ea11a..a1282ca 100644
--- a/test/index/functions/templates.cc
+++ b/test/index/functions/templates.cc
@@ -60,2 +60,17 @@ struct Q2: Q1<T> {
   void h() { f(); }
-};
\ No newline at end of file
+};
+
+template <typename T>
+class SmartPtr {
+  T *t;
+public:
+  T *operator->() {
+    return this->t;
+  }
+};
+
+template <typename T>
+void use_smurt_ptr(SmartPtr<Q1<T>> p) {
+  p->f();
+  p->g();
+}
\ No newline at end of file
diff --git a/test/index/functions/templates.snapshot.cc b/test/index/functions/templates.snapshot.cc
index c3fddb3..ad77484 100644
--- a/test/index/functions/templates.snapshot.cc
+++ b/test/index/functions/templates.snapshot.cc
@@ -138 +138,31 @@
   };
+  
+  template <typename T>
+//                   ^ definition local 14
+  class SmartPtr {
+//      ^^^^^^^^ definition [..] SmartPtr#
+    T *t;
+//  ^ reference local 14
+//     ^ definition [..] SmartPtr#t.
+  public:
+    T *operator->() {
+//  ^ reference local 14
+//     ^^^^^^^^ definition [..] SmartPtr#`operator->`(155dc7f103cdb9db).
+      return this->t;
+//                 ^ reference [..] SmartPtr#t.
+    }
+  };
+  
+  template <typename T>
+//                   ^ definition local 15
+  void use_smurt_ptr(SmartPtr<Q1<T>> p) {
+//     ^^^^^^^^^^^^^ definition [..] use_smurt_ptr(cde7596607162187).
+//                   ^^^^^^^^ reference [..] SmartPtr#
+//                            ^^ reference [..] Q1#
+//                               ^ reference local 15
+//                                   ^ definition local 16
+    p->f();
+//  ^ reference local 16
+    p->g();
+//  ^ reference local 16
+  }