feat: Show a documentation example for basic CRUD operations using UTApi and Next AppDir

[Elkjdsvn]

Describe the feature you'd like to request

Title is pretty self explanatory but it would be very nice to have the implementation of UTApi getFiles/listFiles/deleteFiles calls.
As a very young dev I don't want to make too big mistakes and I'm scared of leaking something since the new AppDir model is really abstract on certain parts (i.e Server Actions)

Describe the solution you'd like to see

Just a few files showing an opinion from the maintainers on how to deal with it regarding the AppDir model

Additional information

No response

[markflorkowski]

Really like this idea, will probably try to take swing at it in the next week or two if nobody else jumps on it first!

[Elkjdsvn]

Nice !

If you've got some docs on how to do a clean PR for the current repo, I may give it a try too because I would like to contribute.
I just don't want the lack of experience to make me submit something badly formatted or not following UploadThing's docs' best practices

[markflorkowski]

The only notes I would say are to follow conventional commits for naming your PR and, and include a good description.

Otherwise, take a look at the other items in /examples for an idea on how we typically do them.

Anything else we'll catch in code review 👍