Remove unused APM voice activity detection sub-module

API changes:
- webrtc::AudioProcessing::Config::VoiceDetection removed
- webrtc::AudioProcessingStats::voice_detected deprecated
- cricket::AudioOptions::typing_detection deprecated
- webrtc::StatsReport::StatsValueName::
  kStatsValueNameTypingNoiseState deprecated

PSA: https://groups.google.com/g/discuss-webrtc/c/7X6uwmJarE0

Bug: webrtc:11226,webrtc:11292
Change-Id: I8d008b56708cf62961b9857ec052b59fda3b41bf
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/250666
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Gustaf Ullberg <gustaf@webrtc.org>
Reviewed-by: Sam Zackrisson <saza@webrtc.org>
Reviewed-by: Björn Terelius <terelius@webrtc.org>
Commit-Queue: Alessio Bazzica <alessiob@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#35975}

modules/audio_processing/include/audio_processing.h

@@ -113,8 +113,6 @@ static constexpr int kClippedLevelMin = 70;
 //
 // config.high_pass_filter.enabled = true;
 //
-// config.voice_detection.enabled = true;
-//
 // apm->ApplyConfig(config)
 //
 // apm->noise_reduction()->set_level(kHighSuppression);
@@ -232,11 +230,6 @@ class RTC_EXPORT AudioProcessing : public rtc::RefCountInterface {
       bool enabled = false;
     } transient_suppression;
 
-    // Enables reporting of `voice_detected` in webrtc::AudioProcessingStats.
-    struct VoiceDetection {
-      bool enabled = false;
-    } voice_detection;
-
     // Enables automatic gain control (AGC) functionality.
     // The automatic gain control (AGC) component brings the signal to an
     // appropriate range. This is done by applying a digital gain directly and,