feat(mobx): add drafts and state context

src/mobx/Persistent.ts

@@ -0,0 +1,16 @@
+/**
+ * A data store which is persistent and should cache its data locally.
+ */
+export default interface Persistent<T> {
+    /**
+     * Override toJSON to serialise this data store.
+     * This will also force all subclasses to implement this method.
+     */
+    toJSON(): unknown;
+
+    /**
+     * Hydrate this data store using given data.
+     * @param data Given data
+     */
+    hydrate(data: T): void;
+}