three finger gestures

[carlwgeorge]

I recently saw @isaac-8601 post on Mastodon about the COSMIC workspace plans. In #53 there is an image showing the trackpad gestures for switching workspaces using four fingers. I asked if it was possible for this to work with only three fingers and he suggested I file this issue to discuss it further. Being able to configure the three finger gesture to switch workspaces would be adequate, but I also think it makes sense to consider this as the default behavior. I've been using GNOME and recently switched from a vertical workspace extension that used four fingers for this action to one that only needs three fingers, and I think it's a much more comfortable gesture.