Agent feature usage metrics (#3346)

* agent feature usage metrics

* generalized feature telemetry via dialogs

* renamed eventName property to dialogName

* made dialogName an optional field

src/sql/sqlops.proposed.d.ts

@@ -839,7 +839,7 @@ declare module 'sqlops' {
 			 * Create a dialog with the given title
 			 * @param title The title of the dialog, displayed at the top
 			 */
-			export function createDialog(title: string): Dialog;
+			export function createDialog(title: string, dialogName?: string): Dialog;
 
 			/**
 			 * Create a dialog tab which can be included as part of the content of a dialog
@@ -951,6 +951,12 @@ declare module 'sqlops' {
 				 */
 				message: DialogMessage;
 
+				/**
+				 * Set the dialog name when opening
+				 * the dialog for telemetry
+				 */
+				dialogName?: string;
+
 				/**
 				 * Register a callback that will be called when the user tries to click done. Only
 				 * one callback can be registered at once, so each registration call will clear