Feature: Add support for application/x-www-form-urlencoded encoding

[Okabintaro]

Hey there, thanks for making this library!

I was trying to use this extension to talk to an API but found out that the params are always encoded as a JSON object, while the API I was using expected application/x-www-form-urlencoded encoding.

I added a new function http_post_form that has the same signature as the old http_post but uses that encoding instead.
Luckily I was able to reuse a lot of code, since the httplib already has a method for the use case that uses a similar map like the headers that get passed in already.

I found it a bit confusing at first that http_post was posting JSON by default so I noted that down in the README.md too.
But I think it might be a good idea to rename http_post to http_post_json in the future. Let me know what you think.
It might also be a good idea to consider adding support for multipart/form-data and arbitrary text/varchar body for other APIs.

I am open for feedback, but I think this would be a useful feature to talk to more APIs.

[lmangani]

Hello @Okabintaro and first of all thanks for your contribution! I think all of your observations make sense - this was an early extension and leaves a bit to be desired (and designed) but we're glad to welcome other contributors and maintainers to merge and include anything integrations need to make the extension as flexible as possible for as many users and usecases.

[lmangani]

PS: Don't worry about the builder errors for now, thinks change in DuckDB build land so I'll try to resolve them (unless there's a code issue, ofc)

[lmangani]

Thanks again @Okabintaro for your contribution and time - the PR has been merged and the new version (0.0.7) submitted to the DuckDB Community Repository in (duckdb/community-extensions#335) I also invited you to the repository as co-maintainer in case you need to make other changes.

[Okabintaro]

Wow, thank you for the fast merge and invitation! This will be useful for work very soon.
I might try implementing the other features I mentioned, but I have no immediate need for those so I am not sure when I get around to that.

[lmangani]

@Okabintaro the latest version is in distribution - could you confirm if it works as desired? Thanks!

[Okabintaro]

I was able to install and use the updated extension from the community repository an hour ago. Thanks again!