[Feature] Fix deprecation warnings for android

[harsimranmaan]

See https://github.com/flutter/flutter/wiki/Upgrading-pre-1.12-Android-projects

Note: /.pub-cache/hosted/pub.dartlang.org/firebase_core-1.0.1/android/src/main/java/io/flutter/plugins/firebase/core/FlutterFirebaseCorePlugin.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.                    
/.pub-cache/hosted/pub.dartlang.org/firebase_storage-8.0.0/android/src/main/java/io/flutter/plugins/firebase/storage/FlutterFirebaseStoragePlugin.java:38: warning: [deprecation] Registrar in PluginRegistry has been deprecated
  public static void registerWith(PluginRegistry.Registrar registrar) { 
                                                ^                       
1 warning                                                               
Note: /.pub-cache/hosted/pub.dartlang.org/firebase_crashlytics-1.0.0/android/src/main/java/io/flutter/plugins/firebase/crashlytics/FlutterFirebaseCrashlyticsPlugin.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.                    
Note: Some input files use or override a deprecated API.                
Note: Recompile with -Xlint:deprecation for details.                    
Note: /.pub-cache/hosted/pub.dartlang.org/firebase_analytics-7.1.1/android/src/main/java/io/flutter/plugins/firebaseanalytics/FirebaseAnalyticsPlugin.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.                    
Note: /.pub-cache/hosted/pub.dartlang.org/package_info_plus-1.0.0/android/src/main/java/dev/fluttercommunity/plus/packageinfo/PackageInfoPlugin.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.                    
Note: /.pub-cache/hosted/pub.dartlang.org/flutter_keyboard_visibility-5.0.0-nullsafety.1/android/src/main/java/com/jrai/flutter_keyboard_visibility/FlutterKeyboardVisibilityPlugin.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.                    
Note: /.pub-cache/hosted/pub.dartlang.org/firebase_auth-1.0.1/android/src/main/java/io/flutter/plugins/firebase/auth/FlutterFirebaseAuthPlugin.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.