Expose transaction::TransactionProgress as public

[boyswan]

Exposing transaction::TransactionProgress will allow customs implementation of extrinsic submission without being bound to signing in subxt.

async fn submit_then_watch<'client>(
    client: &'client Client<DefaultConfig>,
    ext_hash: H256,
    signed_tx: Bytes,
) -> Result<TransactionProgress<'client, DefaultConfig>, parity_scale_codec::Error> {
    let sub = client.rpc().watch_extrinsic(signed_tx).await.unwrap();
    Ok(TransactionProgress::new(sub, client, ext_hash))
}

let events = submit_then_watch(&api, ext_hash, signed_tx)
      .await
      .unwrap()
      .wait_for_finalized_success()
      .await
      .unwrap();

[cla-bot-2021]

User @boyswan, please sign the CLA here.

[niklasad1]

LGTM

[jsdw]

@boyswan looks like it just needs a cargo +nightly fmt to be run to fix the fmt CI and then it should be good to merge :)