Make Phenotype usable

Fix Phenotype, allowing users to manually flip on/off Phenotype Service flags.

Describe the solution you'd like
The ability for users to add Phenotype Service flags per app, much like Firefox's about:config

Doing this will allow users to flip on flags that Google usually push out to internal staff first for testing: https://www.androidpolice.com/android-autos-upcoming-ui-redesign-is-just-looking-more-and-more-like-apple-carplay/

Describe alternatives you've considered
N/A

Additional context
There's already a minimal stub implmented, currently it just returns an empty array
https://github.com/microg/GmsCore/blob/master/play-services-core/src/main/kotlin/org/microg/gms/phenotype/PhenotypeService.kt#L42

From what I can tell, apps that support Phenotype call getConfigurationSnapshot and update their own local SQLite database with flags from GMS.

I think we're missing a method and a field currently resulting in a silent crash (Android Auto as an example)

03-17 12:14:16.231  4640  5694 D GmsPhenotypeSvc: register(com.google.android.libraries.consentverifier#com.google.android.projection.gearhead, 74620914, [Ljava.lang.String;@9cc5e36, null)
03-17 12:14:16.231  4640  5694 D GmsPhenotypeSvc: getConfigurationSnapshot(com.google.android.libraries.consentverifier#com.google.android.projection.gearhead, , null)
03-17 12:14:16.232  4640  4669 D SafeParcel: Unknown field id 12 in com.google.android.gms.clearcut.LogEventParcelable, skipping.
03-17 12:14:16.232  4640  5694 W BinderUtils: Unknown method 5 in com.google.android.gms.phenotype.internal.IPhenotypeService, skipping
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: Unable to update local snapshot for com.google.android.libraries.consentverifier#com.google.android.projection.gearhead, may result in stale flags.
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: java.util.concurrent.ExecutionException: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Class java.lang.Object.getClass()' on a null object reference
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: 	at nzr.s(SourceFile:6)
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: 	at nzr.get(SourceFile:4)
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: 	at nze.o(SourceFile:1)
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: 	at nze.D(SourceFile:2)
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: 	at loj.d(SourceFile:1)
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: 	at lok.run(SourceFile:83)
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: 	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:462)
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: 	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: 	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:301)
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: 	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: 	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: 	at java.lang.Thread.run(Thread.java:920)
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Class java.lang.Object.getClass()' on a null object reference
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: 	at loa.a(SourceFile:6)
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: 	at jdr.run(SourceFile:55)
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: 	at oan.execute(SourceFile:1)
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: 	at jlc.a(SourceFile:8)
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: 	at rcw.d(SourceFile:5)
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: 	at jlo.o(SourceFile:3)
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: 	at ide.l(SourceFile:1)
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: 	at jjd.cl(SourceFile:2)
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: 	at jke.dispatchTransaction(SourceFile:58)
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: 	at btc.onTransact(SourceFile:3)
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: 	at android.os.Binder.execTransactInternal(Binder.java:1208)
03-17 12:14:16.233 12979 13037 W MobStoreFlagStore: 	at android.os.Binder.execTransact(Binder.java:1166)

SafeParcel: Unknown field id 12 in com.google.android.gms.clearcut.LogEventParcelable, skipping.
BinderUtils: Unknown method 5 in com.google.android.gms.phenotype.internal.IPhenotypeService, skipping

Start with play-services-core/src/main/kotlin/org/microg/gms/phenotype/PhenotypeService.kt, especially the stub around getConfigurationSnapshot, then trace the register and IPhenotypeService calls shown in the report. Determine the required response data and missing method or field from the logged failure; done means per-app Phenotype flags can be manually configured and the reported update no longer fails silently.