feat(dia.ToolView): add visibility option callback

[kumilingus]

Description

Add a callback visibility option to toggle the tools' visibility based on the current state of the cell view.

With this option and the change introduced in #2743, the double link tool can be easily implemented as follows:

new dia.ToolsView({
    new linkTools.Remove({
       distance: (linkView) => linkView.getConnectionLength() > 100 ? 20 : '50%'   
    }),
    new linkTools.Remove({
       distance: -20,
       visibility: (linkView) => linkView.getConnectionLength() > 100
    })
})