[FEATURE] Support customized export target in Python SDK

[badmonster0]

We want to allow users to export to customized target defined in Python SDK.

Creating a generic export target can be complex. We want to support a minimal version in the beginning, such as

• Support for specific schema instead of generic schema
• Leave storage backend setup to users (like create tables, create indexes, etc.) - don't support automatic backend setup yet

---

❤️ Contributors, please refer to 📙Contributing Guide.
Unless the PR can be sent immediately (e.g. just a few lines of code), we recommend you to leave a comment on the issue like I'm working on it or Can I work on this issue? to avoid duplicating work. Our Discord server is always open and friendly.