title: Firebase setup - connect to multiple projects
body: <p>We have a "white label" mobile app with plans to provide it to multiple customers.  We would like to rely on Firebase Crashlytics, Push Notifications, Analytics, In App Messaging, Remote Config, Performance Monitoring and other capabilities.  However, this functionality or rather access to some of these capabilities would have to be segregated from our customers.  As creators/owners/maintainers, we would like to keep control (and exclusive access) to Crashlytics, Remote Config or Performance Monitoring, among others, while configuring Push Notifications, Analytics, In App Messaging, etc. to be accessible and "owned" by the customer.  Is there a way to configure an app with multiple Firebase projects or accomplish the above described separation otherwise?  Preferably, there should be a hard separation (e.g. different Firebase projects) vs. a soft one (i.e. permissions within the same project).</p>