ENYO-3625: Fix issue with delayed :active:hover button styling in response to touch

Issue
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There is a delay in triggering `:active:hover` states in recent versions of Chrome for Android.

Fix
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All `:active:hover` styling has been removed, with the `pressed` class being used for `Onyx.Button`, `Onyx.IconButton`, and `Onyx.Slider` by consolidating the FirefoxOS workaround of adding/removing the `pressed` class during the appropriate events. Additionally, `Onyx.RangeSlider` had not been given this workaround previously and was updated as well. Lastly, there were some existing pressed state issues with the sliders, which have also been resolved via the event handlers (the slider knob would lose the pressed state while being dragged if the drag position was no longer on the knob, even if dragging was still active; this behavior seems appropriate for buttons but not slider knobs as the knob is still changing the state of the slider).

Enyo-DCO-1.1-Signed-off-by: Aaron Tam <aaron.tam@lge.com>