AR: use bandpass filter for analog input

Many bad quality analog mics are not centered properly at 1.6V, but stuck at 0V or stuck at 3.3V in silence. The bandpass filter removes DC offsets and improve signal quality.

usermods/audioreactive/audio_reactive.h

@@ -1175,6 +1175,7 @@ class AudioReactive : public Usermod {
           DEBUGSR_PRINTLN(F("AR: Analog Microphone (left channel only)."));
           audioSource = new I2SAdcSource(SAMPLE_RATE, BLOCK_SIZE);
           delay(100);
+          useBandPassFilter = true;  // PDM bandpass filter seems to help for bad quality analog
           if (audioSource) audioSource->initialize(audioPin);
           break;
         #endif