Test feasibility of entering offline mode

[ramya-rao-a]

Testing #54354

• any OS @chrmarti

Complexity: 2

• Go through Offline mode for VS Code #54354 (comment) and see if we missed any documenting any feature of VS Code that would make a network request.
• Test the new settings extensions.autoCheckUpdates, npm.fetchOnlinePackageInfo.
• Ensure the Show settings for Online Services in the new settings editor displays all the settings related to features that make network requests.

Also see #55374 for ongoing discussion around the Show settings for Online Services view for more info

[chrmarti]

@ramya-rao-a A few more:

• Icon and badges in the extension editor are loaded from remote IIRC.
• Similarly the markdown previewer can load images from remote.
• The Experiments service.

[chrmarti]

Also: Issue reporter does a duplicate search.

[ramya-rao-a]

Thanks @chrmarti, I've updated #54354 accordingly and will include the above in the documentation.
Will add a setting for experiments. Rest are followups from a user invoked action, so they dont need a setting.