Feature: Include what fields are being deprecated by the connector

### Feature description

Over time, connectors may deprecate configuration fields in favor of others. While these changes are documented in the readme (see [conduit-connector-postgres](https://github.com/ConduitIO/conduit-connector-postgres/blob/main/source/config.go#L56) and [conduit-connector-kafka](https://github.com/ConduitIO/conduit-connector-kafka?tab=readme-ov-file#configuration)), we need a programmatic way to determine which fields are deprecated so clients can hide them from their configuration.

~**Update:** Consider a way to mark fields as sensitive if we consider it appropriate as well. This is for clients to determine in which situations is really important to obfuscate its values. If scope becomes to big, consider creating a separate issue for this.~ ⬅︎ [This issue other](https://github.com/ConduitIO/conduit/issues/1608) was created for this purpose.