Support claimsMatchingExpression for `az ad app federated-credential create`

**Related command**

`az ad app federated-credential create`

**Is your feature request related to a problem? Please describe.**

I want to create a federated credential to work with a GitHub merge queue. The subject is not static so I need to use the 'claims matching expression' feature instead.
This appears to not be supported by the Azure CLI. I get this error:
```bash
Property 'subject' cannot be empty.
```

The docs say:
> If `claimsMatchingExpression` is defined, `subject` must be set to null.

**Describe the solution you'd like**

I want to be able to create a federated credential that uses claimsMatchingExpression instead of subject.

```json
{
"name": "MergeQueue",
"issuer": "https://token.actions.githubusercontent.com",
"subject": null,
"claimsMatchingExpression": "claims['sub'] matches 'repo:my-org/my-repo:ref:refs/heads/gh-readonly-queue/main/pr*'",
"description": "Merge queue",
"audiences": [
"api://AzureADTokenExchange"
]
}
```

**Describe alternatives you've considered**

I can't access Entra in the portal in my organisation, but it would work if I could...

**Additional context**