Add Triggers to provider information

Body

We do not have triggers information exposed in provider info but some Providerst already expose some (for example cncf.kubernetes).

What needs to be done:

• add triggers to provider.yaml schema https://github.com/apache/airflow/pull/29950
• add triggers to provider_info schema https://github.com/apache/airflow/pull/33654
• expose triggers via Providers Manager https://github.com/apache/airflow/pull/31278
• add CLI triggers command to airflow providers https://github.com/apache/airflow/pull/31278
• add automated exposure of triggers in the docs
• check trigge classes are present in provider.yaml in unit tests

Committer

• I acknowledge that I am a maintainer/committer of the Apache Airflow project.