### 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.
"""Return tools version."""
        try:
            with subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT) as proc:
                stdoutdata, _ = proc.communicate()
                data = [f for f in stdoutdata.split(b"\n") if f]
                if grep:
                    data = [line for line in data if grep in line]
                if len(data) != 1:
                    return "NOT AVAILABLE"
                else:
                    return data[0].decode()
        except OSError:
            return "NOT AVAILABLE"
    @staticmethod
    def _task_logging_handler():
        """Returns task logging handler."""
        def get_fullname(o):
            module = o.__class__.__module__
            if module is None or module == str.__class__.__module__:
                return o.__class__.__name__  
            else:
                return module + "." + o.__class__.__name__
        try:
            handler_names = [get_fullname(handler) for handler in logging.getLogger("airflow.task").handlers]
            return ", ".join(handler_names)
        except Exception:
            return "NOT AVAILABLE"
    @property
    def _airflow_info(self):