Add ability to change sample rate in the settings menu (#7719)

Add a slider in the audio settings menu to allow users to select a few standard sample rates, those being 44100, 48000, 88200, 96000, and 192000.

include/AudioEngine.h

@@ -50,7 +50,6 @@ class MidiClient;
 class AudioBusHandle;
 class AudioEngineWorkerThread;
 
-
 constexpr fpp_t MINIMUM_BUFFER_SIZE = 32;
 constexpr fpp_t DEFAULT_BUFFER_SIZE = 256;
 constexpr fpp_t MAXIMUM_BUFFER_SIZE = 4096;
@@ -61,6 +60,8 @@ constexpr int BYTES_PER_FRAME = sizeof(SampleFrame);
 
 constexpr float OUTPUT_SAMPLE_MULTIPLIER = 32767.0f;
 
+constexpr auto SUPPORTED_SAMPLERATES = std::array{44100, 48000, 88200, 96000, 192000}; 
+
 class LMMS_EXPORT AudioEngine : public QObject
 {
 	Q_OBJECT

include/SetupDialog.h

@@ -182,6 +182,8 @@ private:
 	QSlider * m_bufferSizeSlider;
 	QLabel * m_bufferSizeLbl;
 	QLabel * m_bufferSizeWarnLbl;
+	int m_sampleRate;
+	QSlider* m_sampleRateSlider;
 
 	// MIDI settings widgets.
 	QComboBox * m_midiInterfaces;