Add legendgrouptitle and legendrank to PlotData

Added missing properties of PlotData

legendgrouptitle: plotly/plotly.js#5260

Plotly attributes file with legendgrouptitle and legendrank right below:
https://github.com/plotly/plotly.js/blob/ab5e16afc34fa4f22efffef129f811381580e0fe/src/plots/attributes.js#L57

Author: mrtnbrst

types/plotly.js/index.d.ts

@@ -1315,6 +1315,8 @@ export interface PlotData {
     fillpattern: Partial<Pattern>;
     showlegend: boolean;
     legendgroup: string;
+    legendgrouptitle: string;
+    legendrank: number;
     parents: string[];
     name: string;
     stackgroup: string;