* Move Code to a submodule
Closes#4901.
* Base Code cache on hash and re-enable node_modules cache
The current setup appears to only rebuild VS Code if the dependencies
change but we need to rebuild it if anything changes.
I also re-enabled the commented out node_modules caches. They look like
they should work to me with the submodule method. I think the problem
occurred because Code itself was being installed in the yarn step.
* Add test extension
This will let us test extension-related features (like the proxy URI).
I removed the environment variables in the script because they override
the ones you set yourself. We still set defaults in constants.ts.
* Add changelog entry for VSCODE_PROXY_URI
* Add terminal test for VSCODE_PROXY_URI
* Update VS Code
This adds the VSCODE_PROXY_URI environment variable.
* Use frozen lockfile for test dependencies in CI
This might be causing more Playwright issues.
* Bump Playwright
Mostly just to trigger a reinstall of dependencies since it is cached
and still failing.
Once updated it errors saying install needs to run so add that too.
