[@types/heremaps] Adding draggable property to AbstractMarker in heremaps (#25017)

* Adding draggable property to AbstractMarker in heremaps

* Fix jsdoc and optional for draggable property to AbstractMarker in heremaps

* Fix jsdoc description for draggable property to AbstractMarker in heremaps

types/heremaps/index.d.ts

@@ -2,6 +2,7 @@
 // Project: https://developer.here.com/
 // Definitions by: Joshua Efiong <https://github.com/Josh-ES>
 //                 Bernd Hacker <https://github.com/denyo>
+//                 Ferdinand Armbruster <https://github.com/fx88>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.1
 
@@ -1634,6 +1635,12 @@ declare namespace H {
              * @returns {H.map.AbstractMarker} - the marker itself
              */
             setIcon(icon: (H.map.Icon | H.map.DomIcon)): H.map.AbstractMarker;
+
+            /**
+             * @property draggable
+             * @description This property ensure that the marker can receive drag events.
+             */
+            draggable?: boolean;
         }
 
         namespace AbstractMarker {