Async transfer API added

[dmitry-zakablukov]

Good day.

This pr suggests some API updates to support async transfers.

Async transfer usage:

let mut transfer = rusb::Transfer::<'a>::new(&device_handle, 0)?;
transfer.set_transfer_type(rusb::constants::LIBUSB_TRANSFER_TYPE_CONTROL)?;
transfer.set_timeout(1000)?;
transfer.set_endpoint(0)?;

transfer.set_callback(Some(Box::new(move |status, data| {
    // process data
})))?;

transfer.submit_transfer(
    [0u8;10], // data
    0, bm_request_type,
    0, b_request,
    0, w_value,
    0, w_index,
)?;

You can take this changes as a base for your own API or just merge it as is.

[matallui]

typo?

[dmitry-zakablukov]

Yes, thank you, fixed.

[a1ien]

I think it's good to split this PR.
Move log commit to separate PR.

[dmitry-zakablukov]

@a1ien , done: #76

[samueldotj]

@a1ien are you planning to merge this patch?

[a1ien]

I want find some time to rework. And maybe as separate crate in workspace. Because I want more test.
I promise that I find time until mid-autumn to check and rewrite and made some async support in rusb.

P.S. I am now in relocation process so to much new things in new country :)

[a1ien]

Closed in favor of #143