ENH: Add abstraction that represents family of models that classify frames / time bins from spectrogram windows #603
Description
as described in #536 (comment)
This class WindowedFrameClassificationModel will sub-class a Model class that itself sub-classes lightning.LightningModule. Methods of WindowedFrameClassificationModel will contain logic from original vak.engine.Model class methods, that are coupled very tightly to the task of assigning labels to time bins / frames of windows from spectrograms.