[Bug] When `crossOriginExtensionHost` FF is true some extensions won't load

MR: Pending...

Description

As a follow-up to https://gitlab.com/gitlab-org/gitlab-web-ide/-/issues/150+, we need to improve our approach here since some extensions pull resources after their initialization. These resources run into CORS issues and prevent the built-in extensions from working.

From this discussion:

issue (non-blocking): Testing this locally, it looks like there's some extensions which try to pull resources after their initialization...

Screenshot_2024-03-07_at_2.52.16_PM

We'll need to investigate this more. For now, we can still move forward with this MR since the changes are behind a feature flag. 👀

Implementation plan

  1. We need to revisit feat: Proxy extHost load module through message... (gitlab-web-ide-vscode-fork!76 - merged)
  2. Instead of just hooking into loadCommonJSModule, we need to hook into all of fetch. This might need to happen somewhere around here https://gitlab.com/gitlab-org/gitlab-web-ide-vscode-fork/-/blob/4d4f318b4e311e9057a06969dbee6bab6a3c5326/src/vs/workbench/api/worker/extensionHostWorker.ts#L55.
  3. Once the fork change is merged ☝ we need to update the gitlab-web-ide to point to the new version.