Keyboard accessibility for the MelodySandbox field. (#10591)

* Keyboard accessibility for the MelodySandbox field.
* Key navigation
* Focus behaviour
* Refactored common behaviour between MelodySandbox and LED Matrix to extend from abstract class
* Align gallery behaviour with Sound Effect editor

* PR feedback code improvements

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Co-authored-by: Richard Knoll <riknoll@users.noreply.github.com>

Author: glastonbridge