Add possibility to include privileges when dumping the schema

One of the usages we give to the exported dump is to make the review of the changes easier and make sure everything is in sync. As part of that review, it's useful to have the export of the privileges as well.

It would be nice if we could opt in to export that information. I gave one example on [this](https://github.com/amacneil/dbmate/discussions/310) discussion.