LibCpp: Add test for parsing class definitions

Userland/Libraries/LibCpp/Tests/class.ast

@@ -0,0 +1,27 @@
+TranslationUnit[0:0->10:1]
+  StructOrClassDeclaration[0:6->10:1]
+  A
+    C'tor
+      (
+      Parameter[1:6->1:10]
+      z
+        Type[1:6->1:10]
+          int
+      )
+    D'tor
+      (
+      )
+    FunctionDeclaration[3:4->3:14]
+      Type[3:4->3:9]
+        void
+      foo
+      (
+      )
+    VariableDeclaration[6:4->8:0]
+      Type[6:4->6:8]
+        int
+      x
+    VariableDeclaration[9:4->10:0]
+      Type[9:4->9:8]
+        int
+      y

Userland/Libraries/LibCpp/Tests/class.cpp

@@ -0,0 +1,11 @@
+class A {
+    A(int z);
+    ~A();
+    void foo();
+
+private:
+    int x;
+
+public:
+    int y;
+};