Auto install bundle

Automatically install extensions "bundled" with installer on startup.

**Issues**:
* Should appReady in ExtensionManger be used instead?
* Terminology: folder name and location

cc @dangoor @peterflynn 

This is for #9233 
Without waiting on this promise to finish, I get: "extensionManager domain is undefined" and everything fails. Let me know if you can think of a cleaner way to do this.