[Feature Request]: Get app to exceed 'bad' thresholds for ANRs and crash rates

[BenHenning]

Is your feature request related to a problem? Please describe.

The Play Store sometimes will deprioritize apps in search results if they have user-perceived crashes and ANR rates that exceed predetermined thresholds by Google. The Oppia Android app currently exceeds these rates for both metrics.

Describe the solution you'd like

We need to reduce ANRs and crashes such that the app's crash threshold goes below the bad threshold. Here is the current situation:

	Current rate (Play Console)	Current rate (Firebase last 90 days)	Expected rate threshold
Crashes	2.67%	2.87%	<1.09%
ANRs	0.60%	Unknown (not captured by Firebase)	<0.47%

Describe alternatives you've considered

The alternative is not fixing these, which is actually fine while the app is in beta. However, as we approach global availability this becomes more important (especially after GA launch because then Oppia's searchability will directly relate to users' ability to find the app).

Additional context

Key crash clusters that should be fixed:

• [BUG]: Play Console warns about unspecified mutability in PendingIntents #5442 -- currently makes up ~70% of all crashes (per Firebase).
• [BUG]: cT.D - lateinit property profileId has not been initialized #5449 -- currently makes up ~10% of all crashes (per Firebase).
• [BUG]: MediaPlayer can block the main thread (cause of ANR) #5650 -- currently makes up ~53% of all ANRs (per Play Console)--note that this estimate is general for media player issues and the proposed fix in that issue is expected to fix the top 2 ANR clusters and possibly several others caused by general media player problems.

We will need to keep this issue open until we see a release that brings the rates back down. Also, if possible we should try to ensure fixes include regression tests to help prevent the crash returning in the future.

[BenHenning]

NB: making this a soft GA requirement since we will really want these fixed once we're in GA (it's not technically a blocker to prevent GA, but it could affect our ability to reach users once the app is in full production).