Add call_foreign function

[Gsantomaggio]

Signed-off-by: Gabriele Santomaggio g.santomaggio@gmail.com

Tested using:

 let compress = String::from_utf8(vec![b'a'; 20]);
            match compress {
                Ok(v) => {
                    let res = self.call_foreign_function("compress", Some(v.as_ref()));
                    info!("[foreign_test] compress {:?}", res);
                    let resw = self.call_foreign_function("uncompress", Some(res.unwrap().as_ref()));

                    info!("[foreign_test] uncompress {:?}", resw);

                }
                Err(_) => {}
            }

result:

[foreign_test] compress Some([120, 156, 75, 76, 196, 4, 0, 79, 166, 7, 149])
[foreign_test] uncompress Some([97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97])

[zhenjunMa]

I also need this feature

@PiotrSikora could you please review this PR?

[PiotrSikora]

This is blocked on #64, since there were no foreign functions in ABI v0.1.0, which Rust SDK implements. It should be merged over the next few days, and then this can be revived.

(Sorry, I was sure I mentioned this before, but I don't see my comment.)

[jcruger-godaddy]

Seems this can be considered now? Thanks for your work @PiotrSikora

[Gsantomaggio]

Hi @PiotrSikora
Is there something I can do? ( I Opened this PR)
Thank you

[PiotrSikora]

Hi @Gsantomaggio! Sorry for the delay. It looks fine, but I wanted to run some tests and use it with existing foreign functions before merging it. Unfortunately, I'm still wrapped in restarting work on C++ Host (which has a much bigger lead-time) and fixing some recent regressions, and I didn't have time to get back to Rust SDK yet. Hopefully, I'll be able to do that next week.

[PiotrSikora]

A few suggestions (nits + NotFound), but it looks good otherwise.

Thanks and again sorry for the delay!

[Gsantomaggio]

That's interesting, I followed the DCO instruction. but something went wrong.
I am going to close this PR will open another one