adds "showLabels" option

Outside of obvious cases where the switch is controlling a true/false, on/off boolean toggle it is often very helpful to provide text on what values the toggle is moving between. This option allows the easy toggling on and off of these labels.

As more of a side note, this PR also simplifies the "size" naming convention to allow for cross-style adjustments regarding sizing while maintaining namespace purity. This was added to provide a consistent independent sizing style for the labels but could probably be used more broadly within the existing themes if so desired.