Add types for @types/chart.js (tooltip model) (#42740)

* Add new tooltip model types

* Fix mistyping

types/chart.js/index.d.ts

@@ -24,6 +24,7 @@
 //                 Oscar Cabrera <https://github.com/mrjack88>
 //                 Carlos Anoceto <https://github.com/canoceto>
 //                 Nobuhiko Futagami <https://github.com/nobu222>
+//                 Marco Ru <https://github.com/Marcoru97>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.3
 
@@ -370,26 +371,33 @@ declare namespace Chart {
     }
 
     interface ChartTooltipModel {
+        afterBody: string[];
         backgroundColor: string;
+        beforeBody: string[];
         body: ChartTooltipModelBody[];
         bodyFontColor: string;
         bodyFontSize: number;
         bodySpacing: number;
         borderColor: string;
         borderWidth: number;
+        caretPadding: number;
         caretSize: number;
         caretX: number;
         caretY: number;
         cornerRadius: number;
         dataPoints: ChartTooltipItem[];
         displayColors: boolean;
+        footer: string[];
         footerFontColor: string;
         footerFontSize: number;
         footerMarginTop: number;
         footerSpacing: number;
         height: number;
+        labelColors: string[];
+        labelTextColors: string[];
         legendColorBackground: string;
         opacity: number;
+        title: string[];
         titleFontColor: string;
         titleFontSize: number;
         titleMarginBottom: number;