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.cc

@@ -145,7 +145,6 @@ std::string AudioProcessing::Config::ToString() const {
           << NoiseSuppressionLevelToString(noise_suppression.level)
           << " }, transient_suppression: { enabled: "
           << transient_suppression.enabled
-          << " }, voice_detection: { enabled: " << voice_detection.enabled
           << " }, gain_controller1: { enabled: " << gain_controller1.enabled
           << ", mode: " << GainController1ModeToString(gain_controller1.mode)
           << ", target_level_dbfs: " << gain_controller1.target_level_dbfs