v3.5 - Refine KNN training and validation page mechanisms

[r59q]

• You will now have to use a 'train model' button when training the KNN model for the first time
• Fixes a bug where the reconnect prompt would show if the connection prompt fails during the device selection screen
• Creates a Drawer component, which slides up and down with a short animation, allowing for an expanded(open) and collapsed(closed) view
  • This is used on the validation page to hide the confusion matrix

• Adds CSV export of individual recordings
• Increased LiveDataBuffer. Should make the predictions slightly less sluggish on low-power hardware
• Adds fingerprinting as suggested in Add fingerprints to data page #520