Use scale-encode and scale-decode to encode and decode based on metadata (#842)

* WIP EncodeAsType and DecodeAsType

* remove silly cli experiment code

* Get things finally compiling with EncodeAsType and DecodeAsType

* update codegen test and WrapperKeepOpaque proper impl (in case it shows up in codegen)

* fix tests

* accomodate scale-value changes

* starting to migrate to EncodeAsType/DecodeAsType

* static event decoding and tx encoding to use DecodeAsFields/EncodeAsFields

* some tidy up and add decode(skip) attrs where needed

* fix root event decoding

* #[codec(skip)] will do, and combine map_key stuff into storage_address since it's all specific to that

* fmt and clippy

* update Cargo.lock

* remove patched scale-encode

* bump scale-encode to 0.1 and remove unused dep in testing crate

* update deps and use released scale-decode

* update scale-value to latest to remove git branch

* Apply suggestions from code review

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

* remove sorting in derives/attr generation; spit them out in order given

* re-add derive sorting; it's a hashmap

* StaticTxPayload and DynamicTxPayload rolled into single Payload struct

* StaticStorageAddress and DynamicStorageAddress into single Address struct

* Fix storage address byte retrieval

* StaticConstantAddress and DynamicConstantAddress => Address

* Simplify storage codegen to fix test

* Add comments

* Alias to RuntimeEvent rather than making another, and prep for substituting call type

* remove unnecessary clone

* Fix docs and failing UI test

* root_bytes -> to_root_bytes

* document error case in StorageClient::address_bytes()

---------

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

subxt/src/storage/storage_client.rs

@@ -7,6 +7,7 @@ use super::{
         validate_storage_address,
         Storage,
     },
+    utils,
     StorageAddress,
 };
 
@@ -57,6 +58,27 @@ where
     ) -> Result<(), Error> {
         validate_storage_address(address, &self.client.metadata())
     }
+
+    /// Convert some storage address into the raw bytes that would be submitted to the node in order
+    /// to retrieve the entries at the root of the associated address.
+    pub fn address_root_bytes<Address: StorageAddress>(
+        &self,
+        address: &Address,
+    ) -> Vec<u8> {
+        utils::storage_address_root_bytes(address)
+    }
+
+    /// Convert some storage address into the raw bytes that would be submitted to the node in order
+    /// to retrieve an entry. This fails if [`StorageAddress::append_entry_bytes`] does; in the built-in
+    /// implementation this would be if the pallet and storage entry being asked for is not available on the
+    /// node you're communicating with, or if the metadata is missing some type information (which should not
+    /// happen).
+    pub fn address_bytes<Address: StorageAddress>(
+        &self,
+        address: &Address,
+    ) -> Result<Vec<u8>, Error> {
+        utils::storage_address_bytes(address, &self.client.metadata())
+    }
 }
 
 impl<T, Client> StorageClient<T, Client>