Add a way to export/download a private file

[distinctgrey]

Steps to reproduce: while working in the Electron app, click the export action on a Swagger file.

Expected behavior: file download or new window with raw Swagger JSON

Actual behavior: link opens in browser, and returns HTTP 404 since I'm not authenticated with my Stoplight user in the browser.

Temporary workaround: make sure you're authenticated on next.stoplight.io in the browser as well, then click the link from within the app.

[lott-ai]

I like the "Download File" idea while in the desktop app. I think this should still be separate from the export URL though. The export URL is helpful for sharing or importing without needing the actual file. If the project is marked as "public" you won't need to authenticate to view the export.

Another idea would be to allow generating a "Public export URL" for a file or project. Or allowing to generate an access token to view the export of a private file.