Improve the look of the widget

[smichel17]

The widget right now is just an ugly gray box with a pause and play icon on it. By contrast, the quick settings tile is able to communicate whether the filter is on or off while still using the outline of the Red Moon logo -- that's useful information and looks much nicer.

I'd like to get the widget at least on par with the tile, but I don't want to spend a ton of time on this. Therefore, the tools we have to work with are:

• Which icons represent on and off states (shape, color, transparency can all change)
• Some simple animation (eg, an icon slides up into frame, or fades in).

[smichel17]

When we do this, we should also change the look of the shortcut "widget", if possible, to something simple like the :arrows_counterclockwise: emoji, so that people get the idea that the real widget is the right one to use.

Since this will require people to recreate the widget to the updated look, it's a good time to change the package name— see #297