Get chart context from custom toolbar icon click

[mtinnes]

Is your feature request related to a problem? Please describe.
Would like to reference chart data from custom toolbar icon click handler.

Describe the solution you'd like
As with the events handler, it would be nice to have chart context provided to the custom toolbar icon click handler. Something like this:

toolbar: {
                    tools: {
                        customIcons: [{
                            title: 'Download',
                            class: 'custom-icon',
                            index: 4,
                            click: function (e, chart, options) {
                                console.log('got it');
                            }
                        }]
                    }
                }

[junedchhipa]

Sure, added it.
The order of the params will be

click: function (chart, options, e) {
  console.log('got it');
}