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/dynamic.rs

@@ -12,6 +12,7 @@ use crate::{
         Metadata,
     },
 };
+use scale_decode::DecodeAsType;
 
 pub use scale_value::Value;
 
@@ -43,13 +44,11 @@ pub struct DecodedValueThunk {
 }
 
 impl DecodeWithMetadata for DecodedValueThunk {
-    type Target = Self;
-
     fn decode_with_metadata(
         bytes: &mut &[u8],
         type_id: u32,
         metadata: &Metadata,
-    ) -> Result<Self::Target, Error> {
+    ) -> Result<Self, Error> {
         let mut v = Vec::with_capacity(bytes.len());
         v.extend_from_slice(bytes);
         *bytes = &[];
@@ -72,10 +71,11 @@ impl DecodedValueThunk {
     }
     /// Decode the SCALE encoded storage entry into a dynamic [`DecodedValue`] type.
     pub fn to_value(&self) -> Result<DecodedValue, Error> {
-        DecodedValue::decode_with_metadata(
+        let val = DecodedValue::decode_as_type(
             &mut &*self.scale_bytes,
             self.type_id,
-            &self.metadata,
-        )
+            self.metadata.types(),
+        )?;
+        Ok(val)
     }
 }