Specify order of columns on BigQuery

[agrass]

Tell us about the problem you're trying to solve

I'm trying to specify the order of the columns on bigQuery integration. Right now is using random order.

Describe the solution you’d like

Would be awesome to have some order number on the schema that would be used on BigQuery at the moment of creation on BigQuery or other destinations, also would be a good solution to consider as default order the same order of the schema, I would expected that as a normal behavior.

Are you willing to submit a PR?

Yes, if you can guide me a little how to start with this.