audioflinger: refactor EffectModule class

Introduce a class EffecBase as a parent class of
EffectModule with default implementation for handles management,
basic properties storage and state management.

Bug: 146177259
Test: CTS: AudioEffectTest, EqualizerTest, VisualizerTest,
AudioPreProcessingTest
Test: manual test: Play Music EQ settings, Duo EAC and NS
Change-Id: Id91cef9db6b4f6be0d2e77a8b4afcbdc7234e519
diff --git a/services/audioflinger/AudioFlinger.h b/services/audioflinger/AudioFlinger.h
index eb851ec..5f55ddb 100644
--- a/services/audioflinger/AudioFlinger.h
+++ b/services/audioflinger/AudioFlinger.h
@@ -533,6 +533,7 @@
     class AsyncCallbackThread;
     class Track;
     class RecordTrack;
+    class EffectBase;
     class EffectModule;
     class EffectHandle;
     class EffectChain;