[Website] Support source maps shipped with plugins

[adamziel]

When you install your WordPress plugin in Playground, Chrome won't use the source maps shipped with your plugin. That makes debugging the JavaScript more difficult. I'm not sure about Firefox and Safari, but for Chrome it's related to a known browser issue:

https://issues.chromium.org/issues/41486524?pli=1

cc @juanmaguitar

[adamziel]

...well, there may be something we can do.

Say Playground had a bidirectional connection with the playground.wordpress.net server. Then, the server could notice a request to a scoped URL, request the resource from the client, and use it to respond. The same data flow could also be used to implement sharing a public Playground URL – in that scenario, someone else would be able to request resources from my browser.

[juanmaguitar]

It looks like the same issue is happening in Firefox as well

[adamziel]

The server-side proxy would also solve for #2923 🤔