feat(ec2): expose interface endpoint service shortname (aws#20965)

This PR exposes the short name of the InterfaceVpcEndpointService as an additional property. This helps constructs getting it as a param to derive the service name without parsing regional reverse-FQDNs.

As it only adds a property, I think no readme change is needed here.

----

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packages/@aws-cdk/aws-ec2/lib/vpc-endpoint.ts

@@ -316,10 +316,15 @@ export class InterfaceVpcEndpointAwsService implements IInterfaceVpcEndpointServ
   public static readonly XRAY = new InterfaceVpcEndpointAwsService('xray');
 
   /**
-   * The name of the service.
+   * The name of the service. e.g. com.amazonaws.us-east-1.ecs
    */
   public readonly name: string;
 
+  /**
+   * The short name of the service. e.g. ecs
+   */
+  public readonly shortName: string;
+
   /**
    * The port of the service.
    */
@@ -348,6 +353,7 @@ export class InterfaceVpcEndpointAwsService implements IInterfaceVpcEndpointServ
     });
 
     this.name = `${prefix || defaultEndpointPrefix}.${region}.${name}${defaultEndpointSuffix}`;
+    this.shortName = name;
     this.port = port || 443;
   }
 

packages/@aws-cdk/aws-ec2/test/vpc-endpoint.test.ts

@@ -268,6 +268,13 @@ describe('vpc endpoint', () => {
 
     });
 
+    describe('interface endpoint retains service name in shortName property', () => {
+      test('shortName property', () => {
+        expect(InterfaceVpcEndpointAwsService.ECS.shortName).toBe('ecs');
+        expect(InterfaceVpcEndpointAwsService.ECR_DOCKER.shortName).toBe('ecr.dkr');
+      });
+    });
+
     describe('add interface endpoint to looked-up VPC', () => {
       test('initial run', () => {
         // GIVEN