fix(kms): aliasName references alias itself (under feature flag)

[kaizencc]

Fixes #25761

The existing behavior was that alias.aliasName was always a raw string, so properties like keyId and keyArn depended on a raw string and not a reference to the alias itself. This behavior is preserved.

Under a new feature flag, const KMS_ALIAS_NAME_REF = '@aws-cdk/aws-kms:aliasNameRef', we instead use a reference to the aliasName output itself, which means that properties that depend on aliasName now depend on the alias. In turn, the alias depends on the key. This allows the expected behavior where specifying something like alias.keyArn() depends on the key.

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[gitpod-io]

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Thank you for contributing! Your pull request will be updated from main and then merged automatically (do not update manually, and be sure to allow changes to be pushed to your fork).

[ottokruse]

This change breaks my existing code, because of the Ref I now get a CloudFormation circular dependency. I want the raw string, not the Ref. Is there a way to get the raw string?

[ottokruse]

This is because I want to use the name of the alias in a condition statement of my key policy

[ottokruse]

FYI doing this to get the raw string again:

(key.node.defaultChild as cdk.aws_kms.CfnAlias).aliasName