We want to support extensions depending on other extensions and having that transitive closure installed when installing the first one. Eg. vscode-go could depend on vscode-go-syntax.

This requires vsce work:

• Figure out a syntax for package.json to indicate extension dependencies: extensionDependencies
• Map dependencies to version properties, queriable from the Marketplace: Add extension dependencies as a version property vscode-vsce#124
  • Property: Microsoft.VisualStudio.Code.ExtensionDependencies

For vscode:

• Figure out extension transitive closure, from version properties.
• Render that in the extension editor. Tracked in Show the user the list of extensions that will be installed #12756
• Figure out how to notify user that more extensions will be installed (Install all, Install this extension only, Cancel)

We're leaving Uninstall out of the story for now.