Refactor SequencerProvider and PatternEngineProvider for improved state management and logging

Commit notes

- Introduced SequencerProviderInner to encapsulate state management and improve the handling of playback state. - Updated PatternEngineProvider to enhance logging for better debugging during instrument step updates. - Adjusted BPM state initialization to utilize props for better flexibility. - Removed unused handlePackGenerated function in SequencerPage for cleaner code.