Make next steps clearer when you're logged out and want to upload something

Increasing Access

Just came across a user who didn't see an option to upload files anywhere, and saw the following p5 warning and assumed it meant you have to run a local web server in order to serve images for p5 to load:

p5.js says: It looks like there was a problem loading your image. Try checking if the file path (https://preview.p5js.org/some_file_name_here.png) is correct, hosting the file online, or running a local server.

Probably having some indication in the UI that uploading is available as a feature, just not while logged out, would help address this confusion and stop some users from following a complicated fruitless path.

Feature enhancement details

Currently, the upload option is just gone when you're logged out, only showing options for creating new text files. Maybe we can keep the upload options in the files menu, but greyed out, with a tooltip saying "log in to enable uploads"?

Start by locating the files-menu UI and the logged-out state that hides upload options. Compare the available controls for logged-out users with the proposed disabled upload entries and login tooltip; done means the upload options are visibly present, unavailable until login, and explain how to enable them.