Option to remove hover delay

REQUEST: Add an option to have no hover delay over a category button

When hovering over a category button, it would be nice if the load was absolutely as fast as possible. On my machine, the delays is about half second

A wild guess, is that this is contributing to the delay: https://gitlab.xfce.org/panel-plugins/xfce4-whiskermenu-plugin/-/blob/master/panel-plugin/category-button.cpp#L43

So, how about removing that 150ms delay (make it 1ms?) and then I guess the rest of the delay is something else.

Great tool. I've been using it for about a year.