Add for-await support for streaming

[Minigugus]

Fix #1

This PR is a very simple and naive implementation of for-await for consuming stream. I added tests and updated the README.

Feel free to update or close if you have a better idea.

Otherwise, awesome project, thank you 😄

let result = 0
for await (const { generate_series: x } of sql`select * from generate_series(1, 100000)`)
  result += x;
return [4699408878, result]

[porsager]

Hey @Minigugus ... Thanks a lot for the kind words and the PR.

As you might have seen in the #1 issue I've already got a working branch here: https://github.com/porsager/postgres/tree/cursor which I realize I should have made a PR for so that it was visible work was already under way.

With regards to your implementation here, while it works, it will fill up memory with all the rows coming from the database which I don't feel is what a user will expect if using for await.

I'll be finishing up my work in the cursor branch this or next week which will also include for await support, so I hope you're ok with me closing out this PR?

[Minigugus]

Argh, too fast, my bad 😅

Your implementation will obviously be better than mine, I'm closing this PR 😉

Keep up the great work 😄

[porsager]

Cool :)

And thanks, I'll do my best.