feat: support "no network"

[BoxBoxJason]

Note

For context, I deployed a self hosted version of excalidash on a kubernetes cluster. I configured OIDC for authentication.
I am working in an offline context, with 0 access to internet for both the browser and the pods (backend & frontend).

Description

I found two problems in the frontend caused by this "no internet" mode

• It is also currently impossible to "upload" an image using the "Insert Image" button, nothing happens when I press the button. (probably because it failed to fetch https://unpkg.com/@excalidraw/excalidraw@0.17.6/dist/excalidraw-assets/vendor-677e88ca78c86bddf13d.js when loading the page)
• It is currently impossible to "Export Image" when you cannot access https://unpkg.com (no network connection).
  This error pops up:

Loading chunk 4736 failed.
(error: https://unpkg.com/@excalidraw/excalidraw@0.17.6/dist/excalidraw-assets/vendor-677e88ca78c86bddf13d.js)

These errors are expected because the user's browser cannot access any external internet dependency.

Suggestion

I see two options to fix this problem:

• Could the frontend dependencies be packaged and served via the frontend container so the browser does not need to fetch external dependencies ?
• Else, could we use some sort of environment variable to configure the URL for FRONTEND_DEPENDENCIES_URL=https://unpkg.com so I can configure a proxy where the dependencies would be placed ?

I would prefer the first option, but tell me which one you prefer (or suggest something else), I can create a PR for that.