feat(openapi): Add modified typescript-fetch template

This template is modified from the original one, to handle multiple
status-code handling of response.

Don't ask me how they work, I don't quite understand them in depth...

openapi-template/ApiEntitiesSelectors.mustache

@@ -0,0 +1,5 @@
+export let getApiEntitiesState: (state: any) => any = (state: any) => state.app.apiEntities;
+
+export function setApiEntitiesStateGetter(getter: (state: any) => any) { // Use this to customize the location where you have placed your ApiEntitiesRecord in your project.
+    getApiEntitiesState = getter;
+}