Studio CLI: Fix Windows E2E tests

[fredrikekelund]

Related issues

• Fixes STU-1155

Proposed Changes

This PR fixes the Windows E2E tests by making the following changes:

• Disconnect from pm2 in the site list --watch command in response to SIGINT and SIGTERM signals. Without this, the site list --watch command couldn't be aborted with Ctrl+C, but also, the electronApp.close() call would hang because the site watcher child process would never quit.
• Revert the changes from Sync site list when CLI creates sites while app is running #2313, because they make the E2E tests fail. See Sync site list when CLI creates sites while app is running #2313 (comment)
• Run the site stop-all command in a detached and unrefed process to ensure the Electron app can quit independently of it. This is relevant because we trigger this command when the app quits, and it takes a few seconds to complete. We could look into improving the performance of this command, but regardless, this implementation is the way to go because it guarantees correct behavior.
• Don't remove session data files in E2ESession::cleanup. This method was giving us a lot of grief, especially on Windows, because some processes kept holding file locks, preventing the directory from being removed. After trying several retry strategies to remove the directories, I settled on simply leaving them in place. See code comment for more details about why I think this is a viable strategy.
• Increase the locator timeout in several places in e2e/blueprints.test.ts. We are investigating site creation performance on the dev/studio-cli-i2 branch, so hopefully this isn't needed long-term (it might not even be needed on CI), but I had to do it to get the tests to pass on my Windows VM.
• Playground was logging warnings about themeZipFile and pluginZipFile being deprecated, so I also took the opportunity to replace those keys with themeData and pluginData in the test fixtures.
• Start the site watcher (site list --watch) and wait for the spawn event from the child process before creating the main app window.

Testing Instructions

CI should pass.

Pre-merge Checklist

• Have you checked for TypeScript, React or other console errors?

[fredrikekelund]

The studio site list --watch command would previously not interrupt in response to Ctrl+C