Provide chartjs object when Chart component is totally instantiated

[juanparati]

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I observed that that Chart component wrapper instantiate the ChartJS dynamically, and this makes difficult to load and register ChartJS plugins.

I propose to expose the ChartJS component as soon that object is instantiated, so parents components can register plugins.

It is very easy to achieve replacing the method initChart method with something like:

protected initChart() {
        import('chart.js/auto').then((module) => {
            if (this.chart) {
                this.chart.destroy();
                this.chart = null;
            }

            if (module && module.default) {
                this.chart = new module.default(this.canvas, {
                    // @ts-ignore
                    type: this.type,
                    // @ts-ignore
                    data: this.data,
                    options: this.options
                });

                this.$emit('loaded', this.chart);
            }
        });
    }

Note that this.$emit('loaded', this.chart) was added passing the ChartJS object.