App <> VS Code onboarding

[taylorsperry]

Requirements:

• When a user downloads the app and chooses the option to install the VS Code extension, they won't have to click a button to "connect to the app." The editor will connect to the app automatically and it will "know" about all the repos that the app has generated embeddings for.
• If a user has the editor extension, but not the app, the editor will prompt the user to download the app. Once they have the app running, the editor will be able to detect that the app is installed and the user won't have to click a button to "connect the app."

Related PRs:

• Cody: new app-first auth flow #53434
• App: Generate token and write app token file for seamless integration with editor extensions #53782
• cody: auto signin with app #53908