Rework Subxt API to support offline and dynamic transactions (#593)

* WIP API changes

* debug impls

* Get main crate compiling with first round of changes

* Some tidy up

* Add WithExtrinsicParams, and have SubstrateConfig + PolkadotConfig, not DefaultConfig

* move transaction into extrinsic folder

* Add runtime updates back to OnlineClient

* rework to be 'client first' to fit better with storage + events

* add support for events to Client

* tidy dupe trait bound

* Wire storage into client, but need to remove static reliance

* various tidy up and start stripping codegen to remove bits we dont need now

* First pass updating calls and constants codegen

* WIP storage client updates

* First pass migrated runtime storage over to new format

* pass over codegen to generate StorageAddresses and throw other stuff out

* don't need a Call trait any more

* shuffle things around a bit

* Various proc_macro fixes to get 'cargo check' working

* organise what's exposed from subxt

* Get first example working; balance_transfer_with_params

* get balance_transfer example compiling

* get concurrent_storage_requests.rs example compiling

* get fetch_all_accounts example compiling

* get a bunch more of the examples compiling

* almost get final example working; type mismatch to look into

* wee tweaks

* move StorageAddress to separate file

* pass Defaultable/Iterable info to StorageAddress in codegen

* fix storage validation ne, and partial run through example code

* Remove static iteration and strip a generic param from everything

* fix doc tests in subxt crate

* update test utils and start fixing frame tests

* fix frame staking tests

* fix the rest of the test compile issues, Borrow on storage values

* cargo fmt

* remove extra logging during tests

* Appease clippy and no more need for into_iter on events

* cargo fmt

* fix dryRun tests by waiting for blocks

* wait for blocks instead of sleeping or other test hacks

* cargo fmt

* Fix doc links

* Traitify StorageAddress

* remove out-of-date doc comments

* optimise decoding storage a little

* cleanup tx stuff, trait for TxPayload, remove Err type param and decode at runtime

* clippy fixes

* fix doc links

* fix doc example

* constant address trait for consistency

* fix a typo and remove EncodeWithMetadata stuff

* Put EventDetails behind a proper interface and allow decoding into top level event, too

* fix docs

* tweak StorageAddress docs

* re-export StorageAddress at root for consistency

* fix clippy things

* Add support for dynamic values

* fix double encoding of storage map key after refactor

* clippy fix

* Fixes and add a dynamic usage example (needs new scale_value release)

* bump scale_value version

* cargo fmt

* Tweak event bits

* cargo fmt

* Add a test and bump scale-value to 0.4.0 to support this

* remove unnecessary vec from dynamic example

* Various typo/grammar fixes

Co-authored-by: Alexandru Vasile <60601340+lexnv@users.noreply.github.com>

* Address PR nits

* Undo accidental rename in changelog

* Small PR nits/tidyups

* fix tests; codegen change against latest substrate

* tweak storage address util names

* move error decoding to DecodeError and expose

* impl some basic traits on the extrinsic param builder

Co-authored-by: Alexandru Vasile <60601340+lexnv@users.noreply.github.com>

testing/integration-tests/src/utils/wait_for_blocks.rs

@@ -0,0 +1,17 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is dual-licensed as Apache-2.0 or GPL-3.0.
+// see LICENSE for license details.
+
+use subxt::{
+    client::OnlineClientT,
+    Config,
+};
+
+/// Wait for blocks to be produced before running tests. Waiting for two blocks
+/// (the genesis block and another one) seems to be enough to allow tests
+/// like `dry_run_passes` to work properly.
+pub async fn wait_for_blocks<C: Config>(api: &impl OnlineClientT<C>) {
+    let mut sub = api.rpc().subscribe_blocks().await.unwrap();
+    sub.next().await;
+    sub.next().await;
+}