Adjust R8 optimization configs to fix extension issues

Related: https://issuetracker.google.com/issues/233779072

app/proguard-android-optimize.txt

@@ -1,4 +1,3 @@
--allowaccessmodification
 -dontusemixedcaseclassnames
 -verbose
 

app/proguard-rules.pro

@@ -1,11 +1,11 @@
 -dontobfuscate
 
-# Keep extension's common dependencies
--keep class eu.kanade.tachiyomi.source.** { public protected *; } # Avoid access modification
+# Keep common dependencies used in extensions
 -keep,allowoptimization class eu.kanade.tachiyomi.** { public protected *; }
 -keep,allowoptimization class androidx.preference.** { *; }
 -keep,allowoptimization class kotlin.** { public protected *; }
 -keep,allowoptimization class kotlinx.coroutines.** { public protected *; }
+-keep,allowoptimization class kotlinx.serialization.** { public protected *; }
 -keep,allowoptimization class okhttp3.** { public protected *; }
 -keep,allowoptimization class okio.** { public protected *; }
 -keep,allowoptimization class rx.** { public protected *; }
@@ -14,6 +14,9 @@
 -keep,allowoptimization class app.cash.quickjs.** { public protected *; }
 -keep,allowoptimization class uy.kohesive.injekt.** { public protected *; }
 
+# Avoid optimizations, including access modification
+-keep class * { <fields>; <methods>; }
+
 ##---------------Begin: proguard configuration for RxJava 1.x  ----------
 -dontwarn sun.misc.**