feat(cloudwatch): expose dashboardName property on the L2 Dashboard c…

…onstruct (#17721)

Exposes `dashboardName` property on `Dashboard` construct. 

closes issue #17648 
----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/@aws-cdk/aws-cloudwatch/lib/dashboard.ts

@@ -75,6 +75,14 @@ export interface DashboardProps {
  * A CloudWatch dashboard
  */
 export class Dashboard extends Resource {
+
+ /**
+ * The name of this dashboard
+ *
+ * @attribute
+ */
+ public readonly dashboardName: string;
+
  /**
  * ARN of this dashboard
  *
@@ -99,7 +107,7 @@ export class Dashboard extends Resource {
  }
  }
 
- new CfnDashboard(this, 'Resource', {
+ const dashboard = new CfnDashboard(this, 'Resource', {
  dashboardName: this.physicalName,
  dashboardBody: Lazy.string({
  produce: () => {
@@ -115,6 +123,8 @@ export class Dashboard extends Resource {
  }),
  });
 
+ this.dashboardName = this.getResourceNameAttribute(dashboard.ref);
+
  (props.widgets || []).forEach(row => {
  this.addWidgets(...row);
  });