Add pre-commit/test to verify extra links refer to existed classes #28510
Description
Body
We had an issue where extra link class (AIPlatformConsoleLink) was removed in PR without removing the class from the provider.yaml extra links this resulted in web server exception as shown in #28449
The Task:
Add validation that classes of extra-links in provider.yaml are importable
Committer
- I acknowledge that I am a maintainer/committer of the Apache Airflow project.