Integrate Firebase for crash reporting, analytics, and performance monitoring

[vickychijwani]

Fabric was acquired by Google a while ago and their tools are being merged into Firebase. So we'll need to migrate off of Fabric in the coming months. Currently we use these Fabric tools:

• Crashlytics (crash-reporting) - replaced by Firebase Crashlytics
• Answers (analytics) - replaced by Firebase Analytics

While we're at it, Firebase has some other nice tools for things like performance monitoring and server-side app configuration as well. Worth looking into those.

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Todo:

• [x] Integrate Firebase Analytics
• [ ] Integrate Firebase Crashlytics
• [x] Integrate Firebase Performance Monitoring
• [ ] Remove all traces of Fabric

Observations:

• APK size impact with new firebase-core + firebase-perf deps: 9.86 MB -> 10.85 MB (+992 KB)
  • Removing Fabric eventually should offset this