Add support for plugging in Custom SchemaFactory/Envelope for Envelope Schema [DBZ-8967]

Migrated from [DBZ-8967](https://issues.redhat.com/browse/DBZ-8967)

h1. Feature request or enhancement

For feature requests or enhancements, provide this information, please:
h2. Which use case/requirement will be addressed by the proposed feature?

*Debezium (DBZ)* emits standard CDC events and supports the use of custom SMTs to reshape records into the desired format. While SMTs are powerful, they introduce additional overhead when schema is reconstructed . For instance, the Debezium Server Iceberg sink uses the _unwrap_ SMT to convert CDC records into a structure compatible with Iceberg.

Introducing support for configuring or using a custom {{SchemaFactory}} to define the envelope schema can help reduce latency, especially when the sink does not require the standard CDC format.

 
h2. Implementation ideas (optional)

Add a standard interface like AbstractSourceInfoStructMaker (for source info) at Envelop level.