Save the state of PromptQueue and restore it if the application is restarted after a crash

[adolfintel]

I often leave ComfyUI running with a long queue of prompts while I sleep or do other stuff, but sometimes it crashes because it runs out of memory or something and I lose my entire prompt queue and history.

With this simple modification, the state of PromptQueue is saved every time something is added/removed to the queue/history and if the application is restarted after a crash, it automatically reloads the state from this backup and resumes processing it.

It doesn't fully save/restore the state of the application, just the queue and history, but it gets the job done for me.

[TijuanaKez]

Need this.