include variable type information (#202896)

include type information

src/vscode-dts/vscode.proposed.notebookVariableProvider.d.ts

@@ -38,6 +38,9 @@ declare module 'vscode' {
 			An empty string can be used if no value should be shown in the UI.
 		*/
 		value: string;
+
+		/** The type of the variable's value */
+		type?: string;
 	}
 
 }