Add generic create entity support

✨ Allow working with a new (unsaved) entity Active is laying the groundwork for this.

Step 1 to unblocking this would be the server side informing the client side for which entity types this is allowed. Which reminds me of 📌 Update `ApiContentControllers::list()` to expose available content entity operations in `meta` Active .

Ah, @penyaskito already created 📌 Provide the client with permissions flags for create content Active for this! 👍

📌 Provide the client with permissions flags for create content Active is in.