Add PackedRealArray as an alias for Vector<real_t>

(cherry picked from commit 3f469ee4858e559e007a9f812e4d73cea888a23e)

core/variant/variant.h

@@ -70,6 +70,7 @@ typedef Vector<int32_t> PackedInt32Array;
 typedef Vector<int64_t> PackedInt64Array;
 typedef Vector<float> PackedFloat32Array;
 typedef Vector<double> PackedFloat64Array;
+typedef Vector<real_t> PackedRealArray;
 typedef Vector<String> PackedStringArray;
 typedef Vector<Vector2> PackedVector2Array;
 typedef Vector<Vector3> PackedVector3Array;