Enhance sample pack change handling in SequencerProvider and SampleManagementProvider

Commit notes

- Updated handleSamplePackChange to return a Promise for better asynchronous handling. - Introduced coordinated playback stopping before sample pack changes to improve user experience. - Added clearTrackData functionality in worklet communication to manage audio buffers and scheduled events effectively. - Enhanced SequencerProcessor to clear track data, including audio buffers and active voices, during sample pack transitions.