feat(ec2): add mailmanager vpc endpoints (#33996)

### Reason for this change

Add MailManager VPC Endpoint definitions.

### Description of changes

Added static instances `MAILMANAGER` and `MAILMANAGER_FIPS` of `InterfaceVpcEndpointAwsService`.

### Description of how you validated changes

Compared values to [documentation](https://docs.aws.amazon.com/vpc/latest/privatelink/aws-services-privatelink-support.html).

Compared values to output of
```
aws ec2 describe-vpc-endpoint-services \
  --region us-east-1 \
  --filter 'Name=service-name,Values=com.amazonaws.us-east-1.mail-manager,com.amazonaws.us-east-1.mail-manager-fips' \
| jq -r '.ServiceNames[]'
# com.amazonaws.us-east-1.mail-manager
# com.amazonaws.us-east-1.mail-manager-fips
```

### Checklist
- [X] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

----

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

Author: rwie-aws

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

@@ -518,6 +518,8 @@ export class InterfaceVpcEndpointAwsService implements IInterfaceVpcEndpointServ
   public static readonly LOOKOUT_EQUIPMENT = new InterfaceVpcEndpointAwsService('lookoutequipment');
   public static readonly LOOKOUT_METRICS = new InterfaceVpcEndpointAwsService('lookoutmetrics');
   public static readonly LOOKOUT_VISION = new InterfaceVpcEndpointAwsService('lookoutvision');
+  public static readonly MAILMANAGER = new InterfaceVpcEndpointAwsService('mail-manager');
+  public static readonly MAILMANAGER_FIPS = new InterfaceVpcEndpointAwsService('mail-manager-fips');
   public static readonly MAINFRAME_MODERNIZATION = new InterfaceVpcEndpointAwsService('m2');
   public static readonly MAINFRAME_MODERNIZATION_APP_TEST = new InterfaceVpcEndpointAwsService('apptest');
   public static readonly MACIE = new InterfaceVpcEndpointAwsService('macie2');