Implement new API for sign_and_submit_then_watch (#354)

* WIP Implementing new event subscription API

* back to lifetimes, fix example

* no more need for accept_weak_inclusion

* thread lifetime through to prevent 'temporary dropped' issue

* make working with events a little nicer

* Get tests compiling

* fmt and clippy

* _name back to name

* dont take ownership, just have stronger note

* Attempt to fix test

* remove commented-out code

* Add a couple more helper methods and a test

* Remove custom ExtrinsicFailed handling; treat them like other events

* Handle runtime errors in TransactionProgress related bits

* cargo fmt + clippy

* Fix some of the failing tests

* remove unused import

* fix transfer_error test

* Fix compile errors against new substrate latest

* Comment tweaks, and force test-runtime rebuild

* Drop the TransactionProgress subscription when we hit 'end' statuses

* cargo fmt

* find_event to find_first_event and helper to return all matching events

* TransactionProgressStatus to TransactionStatus

* Copy and improve docs on TransactionStatus from substrate

* debug impl for Client to avoid manual debug impls elsewhere

* Add and tweak comments, specifically a note about block inclusion on errors

* clippy + fmt

* Fix docs

* Ignore 'error' statuses and adhere to the substrate docs

* tweak and improve some comments per @dvdplm's suggestions

* Break transaction* structs into separate file

* fmt and fix doc link

tests/integration/frame/system.rs

@@ -29,7 +29,7 @@ use subxt::extrinsic::{
 };
 
 #[async_std::test]
-async fn storage_account() {
+async fn storage_account() -> Result<(), subxt::Error> {
     let alice = PairSigner::<DefaultConfig, _>::new(AccountKeyring::Alice.pair());
 
     let cxt = test_context().await;
@@ -39,23 +39,27 @@ async fn storage_account() {
         .system()
         .account(alice.account_id().clone(), None)
         .await;
-    assert_matches!(account_info, Ok(_))
+
+    assert_matches!(account_info, Ok(_));
+    Ok(())
 }
 
 #[async_std::test]
-async fn tx_remark_with_event() {
+async fn tx_remark_with_event() -> Result<(), subxt::Error> {
     let alice = PairSigner::<DefaultConfig, _>::new(AccountKeyring::Alice.pair());
     let cxt = test_context().await;
 
-    let result = cxt
+    let found_event = cxt
         .api
         .tx()
         .system()
         .remark_with_event(b"remarkable".to_vec())
         .sign_and_submit_then_watch(&alice)
-        .await
-        .unwrap();
+        .await?
+        .wait_for_finalized_success()
+        .await?
+        .has_event::<system::events::Remarked>()?;
 
-    let remarked = result.find_event::<system::events::Remarked>();
-    assert_matches!(remarked, Ok(Some(_)));
+    assert!(found_event);
+    Ok(())
 }