chore: deprecate the ctMock.add() call

The `ctMock.add()` function directly insert objects in the in-memory
store of commercetools mock, which could result in invalid objects being
processed

.changeset/silent-scissors-remain.md

@@ -0,0 +1,5 @@
+---
+"@labdigital/commercetools-mock": minor
+---
+
+Add deprecation warning for `ctMock.add()`

src/projectAPI.ts

@@ -24,6 +24,18 @@ export class ProjectAPI {
 	add<T extends keyof RepositoryMap & keyof ResourceMap>(
 		typeId: T,
 		resource: ResourceMap[T],
+	) {
+		process.emitWarning(
+			"ctMock.add() is deprecated, create resources via regular create endpoints " +
+				"or if you are really sure, use unsafeAdd() (but be aware of potential state issues)",
+			"DeprecationWarning",
+		);
+		this.unsafeAdd(typeId, resource);
+	}
+
+	unsafeAdd<T extends keyof RepositoryMap & keyof ResourceMap>(
+		typeId: T,
+		resource: ResourceMap[T],
 	) {
 		const repository = this._repositories[typeId];
 		if (repository) {