SQLite backend isn't using returning

[andoriyu]

Summary

I would like to use returning branch in update and insert when using sqlite.

Motivation

It's more efficient than looking up by primary id after update.

Additional Information

SQLite's support for RETURNING

[billy1624]

Hey @andoriyu, sorry for the delay but before we proceed with the PR: https://github.com/SeaQL/sea-orm/pull/654 We need to have a consensus on this: https://github.com/SeaQL/sea-orm/pull/654#issuecomment-1177467728