v0.50.0: Integrate frame-decode, redo storage APIs and break up Error. (#2100)

* WIP integrating new frame-decode and working out new storage APIS

* WIP: first pass adding new storage things to subxt-core

* Second pass over Address type and start impl in Subxt

* WIP new storage APIs

* WIP New storage APIs roughly completed, lots of errors still

* Remove PlainorMap enum; plain and map values now use same struct to simplify usage

* Begin 'fixing' errors

* WIP splitting errors and tidying payload/address traits

* Get subxt-core compiling

* Small fixes in subxt-core and remove metadata mod

* subxt-core: cargo check --all-targets passes

* Fix test

* WIP starting to update subxt from subxt-core changes

* WIP splitting up subxt errors into smaller variants

* WIP errors: add DispatchError errors

* Port new Storage APIs to subxt-core

* cargo check -p subxt passes

* Quick-fix errors in subxt-cli (explore subcommand)

* fmt

* Finish fixing codegen up and start fixing examples

* get Subxt examples compiling and bytes_at for constants

* Add some arcs to limit lifetimes in subxt/subxt-core storage APIs

* A little Arcing to allow more method chaining in Storage APIs, aligning with Subxt

* Update codegen test

* cargo check --all-targets passing

* cargo check --features 'unstable-light-client' passing

* clippy

* Remove unused dep in subxt

* use published frame-decode

* fix wasm-example

* Add new tx extension to fix daily tests

* Remove unused subxt_core::dynamic::DecodedValue type

* Update book to match changes

* Update docs to fix more broken bits

* Add missing docs

* fmt

* allow larger result errs for now

* Add missing alloc imports in subxt-core

* Fix doc tests and fix bug getting constant info

* Fix V14 -> Metadata transform for storage & constants

* Fix parachain example

* Fix FFI example

* BlockLength decodes t ostruct, not u128

* use fetch/iter shorthands rather than entry in most storage tests

* Fix some integration tests

* Fix Runtime codegen tests

* Expose the dynamic custom_value selecter and use in a UI test

* Update codegen metadata

* Tidy CLI storage query and support (str,str) as a storage address

* Add (str,str) as valid constant address too

* Show string tuple in constants example

* Via the magic of traits, avoid needing any clones of queries/addresses and accept references to them

* clippy

subxt/examples/storage_fetch.rs

@@ -10,22 +10,23 @@ pub mod polkadot {}
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
     // Create a new API client, configured to talk to Polkadot nodes.
     let api = OnlineClient::<PolkadotConfig>::new().await?;
+    let account = dev::alice().public_key().into();
 
     // Build a storage query to access account information.
-    let account = dev::alice().public_key().into();
-    let storage_query = polkadot::storage().system().account(account);
+    let storage_query = polkadot::storage().system().account();
 
-    // Use that query to `fetch` a result. This returns an `Option<_>`, which will be
-    // `None` if no value exists at the given address. You can also use `fetch_default`
-    // where applicable, which will return the default value if none exists.
-    let result = api
-        .storage()
-        .at_latest()
+    // Use that query to access a storage entry, fetch a result and decode the value.
+    // The static address knows that fetching requires a tuple of one value, an
+    // AccountId32.
+    let client_at = api.storage().at_latest().await?;
+    let account_info = client_at
+        .entry(storage_query)?
+        .fetch((account,))
         .await?
-        .fetch(&storage_query)
-        .await?;
+        .decode()?;
 
-    let v = result.unwrap().data.free;
-    println!("Alice: {v}");
+    // The static address that we got from the subxt macro knows the expected input
+    // and return types, so it is decoded into a static type for us.
+    println!("Alice: {account_info:?}");
     Ok(())
 }