feat(ec2): add Hpc6a instances (#18445)

Add support for Hpc6a instances (high performance computing).

[Announcement](https://aws.amazon.com/about-aws/whats-new/2022/01/amazon-ec2-hpc6a-instances/)

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*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-ec2/lib/instance-types.ts

@@ -725,6 +725,16 @@ export enum InstanceClass {
    * Multi-stream video transcoding instances for resolutions up to 4K UHD, 1st generation
    */
   VT1 = 'vt1',
+
+  /**
+   * High performance computing based on AMD EPYC, 6th generation
+   */
+  HIGH_PERFORMANCE_COMPUTING6_AMD = 'hpc6a',
+
+  /**
+   * High performance computing based on AMD EPYC, 6th generation
+   */
+  HPC6A = 'hpc6a',
 }
 
 /**