### Body

We had an issue where extra link class (`AIPlatformConsoleLink`) was removed in [PR](https://github.com/apache/airflow/pull/26836) without removing the class from the `provider.yaml` extra links this resulted in web server exception as shown in https://github.com/apache/airflow/pull/28449


**The Task:**
Add validation that classes of extra-links in provider.yaml are importable

### Committer

- [X] I acknowledge that I am a maintainer/committer of the Apache Airflow project.
all_integrations = [
        i["integration-name"] for f in yaml_files.values() if "integrations" in f for i in f["integrations"]
    ]
    all_integrations += ["Local"]
    return all_integrations
def check_integration_duplicates(yaml_files: dict[str, dict]):
    """Integration names must be globally unique."""
    print("Checking integration duplicates")
    all_integrations = get_all_integration_names(yaml_files)
    duplicates = [(k, v) for (k, v) in Counter(all_integrations).items() if v > 1]
    if duplicates:
        print(
            "Duplicate integration names found. Integration names must be globally unique. "
            "Please delete duplicates."
        )
        print(tabulate(duplicates, headers=["Integration name", "Number of occurrences"]))
        sys.exit(3)
def assert_sets_equal(set1, set2):