Added callback object to what-changed

Cleaned up more covage in v3 model, we're almost there. My god what a mission this has been.

what-changed/model/components.go

@@ -0,0 +1,19 @@
+// Copyright 2022 Princess B33f Heavy Industries / Dave Shanley
+// SPDX-License-Identifier: MIT
+
+package model
+
+type ComponentsChanges struct {
+	PropertyChanges
+	SchemaChanges         map[string]*SchemaChanges
+	ResponsesChanges      map[string]*SchemaChanges
+	ParameterChanges      map[string]*ParameterChanges
+	ExamplesChanges       map[string]*ExamplesChanges
+	RequestBodyChanges    map[string]*RequestBodyChanges
+	HeaderChanges         map[string]*HeaderChanges
+	SecuritySchemeChanges map[string]*SecuritySchemeChanges
+	LinkChanges           map[string]*LinkChanges
+	// todo:
+	//CallbackChanges map[string]*CallbackChanges
+	ExtensionChanges *ExtensionChanges
+}