Support returning in update many

[Sytten]

Motivation

Currently only update supports the RETURNING clause, but not the update_many.
This is limiting since sometimes you need to use an update_many when the update doesn't support a feature (like a column expression) but then you lose the returning.

Proposed Solutions

Add exec_with_returning to the UpdateMany struct.

Current Workarounds

You have to select back the rows.

[billy1624]

Hey @Sytten, good suggestion!! I think it's possible and nice to have :)

[Sytten]

Thanks!