Make subxt-core ready for publishing (#1508)

* Move Extrinsic decoding things to subxt_core and various tidy-ups

* A couple more fixes and fmt

* first pass moving tx logic to subxt_core

* cargo fmt

* fix wasm example

* clippy

* more clippy

* WIP Adding examples and such

* Move storage functionality more fully to subxt_core and nice examples for storage and txs

* Add example for events

* consistify how addresses/payloads are exposed in subxt-core and add runtime API fns

* Add runtime API core example

* fmt

* remove scale-info patch

* Add a little to the top level docs

* swap args around

* clippy

* cargo fmt and fix wasm-example

* doc fixes

* no-std-ise new subxt-core additions

* alloc, not core

* more no-std fixes

* A couple more fixes

* Add back extrinsic decode test

core/src/client.rs

@@ -0,0 +1,39 @@
+// Copyright 2019-2024 Parity Technologies (UK) Ltd.
+// This file is dual-licensed as Apache-2.0 or GPL-3.0.
+// see LICENSE for license details.
+
+//! A couple of client types that we use elsewhere.
+
+use crate::{config::Config, metadata::Metadata};
+use derive_where::derive_where;
+
+/// This provides access to some relevant client state in signed extensions,
+/// and is just a combination of some of the available properties.
+#[derive_where(Clone, Debug)]
+pub struct ClientState<C: Config> {
+    /// Genesis hash.
+    pub genesis_hash: C::Hash,
+    /// Runtime version.
+    pub runtime_version: RuntimeVersion,
+    /// Metadata.
+    pub metadata: Metadata,
+}
+
+/// Runtime version information needed to submit transactions.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct RuntimeVersion {
+    /// Version of the runtime specification. A full-node will not attempt to use its native
+    /// runtime in substitute for the on-chain Wasm runtime unless all of `spec_name`,
+    /// `spec_version` and `authoring_version` are the same between Wasm and native.
+    pub spec_version: u32,
+    /// All existing dispatches are fully compatible when this number doesn't change. If this
+    /// number changes, then `spec_version` must change, also.
+    ///
+    /// This number must change when an existing dispatchable (module ID, dispatch ID) is changed,
+    /// either through an alteration in its user-level semantics, a parameter
+    /// added/removed/changed, a dispatchable being removed, a module being removed, or a
+    /// dispatchable/module changing its index.
+    ///
+    /// It need *not* change when a new module is added or when a dispatchable is added.
+    pub transaction_version: u32,
+}