Add the ability to save posts as a draft

[zleyyij]

ala @Boxersteavee

Like a draft article, where you write it but not fully so save it to the account but not published, and come back to finish later before publishing the changes.

The changes could probably be stored in localstorage to keep things simple, maybe in the backend?

[Boxersteavee]

Would be nice if it was in the backend, but that could maybe be a bit further down the line, and store in localstorage for now. It would allow picking up from another device (such as a phone or laptop)

[Boxersteavee]

If writing new articles isn't going to be part of MVP then this probably won't be required, and I don't think it would be worth the extra effort to make it into MVP if new articles won't be.