TPCH support

Hi @matthewmturner this is not really an issue but more of a discussion thread, I've recently released https://github.com/clflushopt/datafusion-tpch which acts as a "boilerplate builder" for a TPC-H integration as we discussed a while ago in https://github.com/apache/datafusion/issues/14608. Let me know if it makes your life simpler, it acts as a sort of plugin to expose table functions and other helpers for running TPC-H directly. I am aware that you've integrated tpchgen into dft but let's see if using datafusion-tpch can help make it easier from an integration perspective.

P.S: I would be happy to donate and maintain the project as part of the datafusion-contrib repo if that is something you're open to @alamb suggested that it might help with discoverability in https://github.com/apache/datafusion/issues/14608#issuecomment-3016555361

Review the linked datafusion-tpch project and DataFusion issue 14608 first; this issue names no file, test, or entry point in datafusion-dft. Done is undefined until maintainers decide whether to adopt the proposed integration and clarify its scope.