Browser client for Pelican

[bbockelm]

An important client for Pelican is going to be the browser.

That is, a user should be able to navigate to the director UI, click on a download button, and be taken to a page where they can type in an object name and hit "go". I'd like to have it as a visible demo for December.

The ultimate goal would be some sort of small JavaScript library that someone can embed in their webpage's code. It'd export a function that contacts the director and gets redirected to a new location. The director UI would be a simple wrapper around this library.

For this ticket, I'd like to stick to public data: attempts to access private data should just end in an error.

[CannonLock]

Code is here -> https://github.com/PelicanPlatform/web-client

I have set up this package here -> https://www.npmjs.com/package/@pelicanplatform/web-client

The package includes the Client class which powers the UI in the example here -> https://pelicanplatform.org/web-client/

Current issue is that for these un auth'd requests we need the response header: Access-Control-Allow-Origin: * from both the director and the cache.

Things get trickier with auth but we can discuss that tomorrow.