Expose "plotly_relayouting" event

[Mesya82]

Plotly.js team added very useful event "plotly_relayouting" in v1.48.0(plotly/plotly.js#2082). I think most of us will want to have this event to be exposed in PlotComponent alongside with many other events. I will make Pull request with this feature if I will have time

[andrefarzat]

@Mesya82 amazing. I will be waiting your pull request. Please, don't forget to add an example on the demo page as a test 😸

[andrefarzat]

@Mesya82 please, review the PR #77 😺