Add proguard / R8 integration for the default rule configuration

stream-chat-android-client/src/main/resources/META-INF/proguards/stream-chat-android-client.pro

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+## Stream Chat Android Client Proguard Rules
+
+# Classes that are using with QuerySort can't be minified, because QuerySort uses reflection. If the
+# name of the fields of the classes being used by QuerySort, change, the sort won't work as expected.
+-keep class io.getstream.chat.android.models.** { *; }
+-keep class io.getstream.chat.android.client.api2.model.** { *; }
+
+# ExtraDataDto can't be minified because we check for extraData using reflection in
+# io.getstream.chat.android.client.parser2.adapters.CustomObjectDtoAdapter. If the name of extraData
+# is changed, we will have problem with serialization.
+-keep class * extends io.getstream.chat.android.client.api2.model.dto.ExtraDataDto {
+    public kotlin.collections.Map extraData;
+ }
+
+# Rules necessary for R8 full mode
+-keep class io.getstream.chat.android.client.api2.endpoint.** { *; }
+-keep class io.getstream.chat.android.client.call.RetrofitCall { *; }
+-keep class com.squareup.moshi.JsonReader
+-keep class com.squareup.moshi.JsonAdapter
+-keep class kotlin.reflect.jvm.internal.* { *; }
+
+# Rules to improve the logs by keeping the names of the classes
+-keep class * extends io.getstream.chat.android.client.clientstate.UserState
+
+# Classes that are used by reflection.
+-keep class io.getstream.chat.android.client.notifications.ChatPushDelegate { *; }

stream-chat-android-ui-common/src/main/resources/META-INF/proguards/stream-chat-android-ui-common.pro

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+## Stream Chat Android UI Common Proguard Rules
+
+# Classes that are used by reflection.
+-keep class io.getstream.chat.android.ui.common.notifications.StreamCoilUserIconBuilder { *; }
+-keep class io.getstream.android.push.permissions.snackbar.SnackbarNotificationPermissionHandler { *; }