AIP-38 | Serialize connection types to database

### Body As pre-requisite of #47501 the providers manager must serialize all connectiont ypes into a database table (inlcuding the extra json form field structure) in order to be served by API server to clients. This is a preparation to un-bundle the providers-manager from API server. ### Committer - [x] I acknowledge that I am a maintainer/committer of the Apache Airflow project.