[clang] [clang-tools-extra] [Clang] Make the SizeType, SignedSizeType and PtrdiffType be named sugar types instead of built-in types (PR #143653)

[Matheus Izvekov via cfe-commits]

================
@@ -2258,6 +2258,27 @@ class alignas(TypeAlignment) Type : public ExtQualsTypeCommonBase {
     unsigned NumExpansions;
   };
 
+  enum class PredefinedSugarKind {
+    /// The "size_t" type.
+    SizeT,
+
+    /// The "signed size_t" type.
----------------
mizvekov wrote:

```suggestion
    /// The "ssize_t" type.
```

https://github.com/llvm/llvm-project/pull/143653