feat(sandpack): css url processing

[DeMoorJasper]

What kind of change does this PR introduce?

Process css urls

Closes CSB-4095

[linear[bot]]

CSB-4095 Bundler: CSS url ressources are not being resolved

CodeSandbox: https://codesandbox.io/s/f4msyx?file=/src/App.tsx:143-168

The sandbox above is trying to load an icon library, which is pretty much a CSS file with some fonts call. However, the font calls are resolving to the sandbox itself (https://f4msyx.csb.app/fonts/primeicons.ttf) instead of the node_modules content.

Can we load the CSS as a file instead of injecting it into the body? Or what is the possible solution for it?

Screenshot 2022-04-11 at 14.20.34.png

[codesandbox-ci[bot]]

This pull request is automatically built and testable in CodeSandbox.

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Latest deployment of this branch, based on commit b45b0ef5c9d24c1d86b53f98e0149d11dd921877:

Sandbox	Source
Notifications Test	Configuration

[lbogdan]

Build for latest commit https://github.com/codesandbox/codesandbox-client/pull/6655/commits/b45b0ef5c9d24c1d86b53f98e0149d11dd921877 is at https://pr6655.build.csb.dev/s/new.