Support V16 metadata and refactor metadata code (#1967)

* WIP integrate unstable v16 metadata into Subxt

* first pass moving retain to the CLI tool

* Remove otuer enum variant stripping and move now simpler strip_metadata to new crate. test it

* tidyup to use stripmetadata package etc

* Fix / comment out tests

* fmt

* clippy

* Fix wasm example

* wasm-example fix

* wasm-example fix

* Maske sure to move IDs around after types.retain()

* fmt

* Tweak comment

* Find dispatch error separately to avoid issues during mapping

* Expose associated type information in pallet metadata

* Hopefully fix flaky archive RPC

* remove unwanted temp file

* Address nits

* Add back commented-otu tests and address review comments

* use either, and simplify for_each

utils/fetch-metadata/Cargo.toml

@@ -11,7 +11,7 @@ license.workspace = true
 repository.workspace = true
 documentation.workspace = true
 homepage.workspace = true
-description = "subxt utils fetch metadata"
+description = "subxt utility to fetch metadata"
 
 [features]
 url = ["dep:jsonrpsee", "dep:tokio", "dep:url", "frame-metadata"]