[clangd][NFC] Make Located::operator->() use pointer sematics

[njames93]

Summary

This enables using the arrow operator to access members of the contained item.

Located<std::string> X;
const char* CStr = X->c_str();

This is inline with how classes like Optional handle the arrow operator.

[kadircet]

Ah thanks for catching this. LGTM!

clang-tools-extra/clangd/ConfigFragment.h

 namespace config {
 
 /// An entity written in config along, with its optional location in the file.
 template <typename T> struct Located {
   Located(T Value, llvm::SMRange Range = {})
       : Range(Range), Value(std::move(Value)) {}
 
   llvm::SMRange Range;
-  T &operator->() { return Value; }
-  const T &operator->() const { return Value; }
+  T *operator->() { return &Value; }
+  const T *operator->() const { return &Value; }
   T &operator*() { return Value; }
   const T &operator*() const { return Value; }
 
 private:
   T Value;
 };
 
 /// A chunk of configuration obtained from a config file, LSP, or elsewhere.