[Feature] Support for the creation of composite primary keys using database, table, and existing primary key in Paimon.

[ElancerBlack]

Search before asking

• I searched in the issues and found nothing similar.

Motivation

Although Paimon supports synchronizing multiple MySQL tables into a single table, there is a possibility of duplicate primary keys across these tables, which could result in multiple records being merged into one. Therefore, it would be beneficial for Paimon to support the formation of composite primary keys using the database name, table name, and existing primary key.

Solution

No response

Anything else?

No response

Are you willing to submit a PR?

• I'm willing to submit a PR!

[TaoZex]

Please assign to me. Thanks @yuzelin

[TaoZex]

I will commit code after #2734 merged.