Address performance of tab loading during first chord playback

[Devin-Mix]

Currently, generation of the playback audio track, tone wave track, and input device recording session created during the recording state all occur when the first chord shown in the GUI is intended to be struck. In practice, this creates a significant lag spike which causes the GUI and audio tracks to become desynchronized. To address this, those same audio-related tasks should be handled when the GUI Event Broker or Recording State Manager (whichever is more appropriate) are prompted to start a new recording session. This will shift the delay to the start of the playback session which, while still not ideal in cases where the user's chord falling time is set to a low value, will be significantly less noticeable or disruptive.