CloudFormation: validate stack name prior to publish

If you enter a stack name such as ABC, the publish will get to the final stage of cloudformation and then will give an error:

Error creating CloudFormation change set: 1 validation error detected: Value 'ABC' at 'stackName' failed to satisfy constraint: Member must satisfy regular expression pattern: [a-zA-Z][-a-zA-Z0-9]*|arn:[-a-zA-Z0-9:/._+]*

Please can you add this constraint to the AWS Publish dialog stackname field.

Start with the AWS Publish dialog's stack name field and trace where its value is validated before CloudFormation publishing. Verify that names such as ABC are rejected before publish, while values matching the reported CloudFormation constraint can proceed without this validation error.

Written by the indexing model from the issue text.