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

Cargo.lock

@@ -5255,6 +5255,7 @@ dependencies = [
  "subxt-codegen",
  "subxt-metadata",
  "subxt-utils-fetchmetadata",
+ "subxt-utils-stripmetadata",
  "syn 2.0.87",
  "thiserror 2.0.12",
  "tokio",
@@ -5367,6 +5368,7 @@ dependencies = [
  "parity-scale-codec",
  "scale-info",
  "sp-crypto-hashing",
+ "subxt-utils-stripmetadata",
  "thiserror 2.0.12",
 ]
 
@@ -5453,6 +5455,15 @@ dependencies = [
  "url",
 ]
 
+[[package]]
+name = "subxt-utils-stripmetadata"
+version = "0.41.0"
+dependencies = [
+ "either",
+ "frame-metadata 20.0.0",
+ "scale-info",
+]
+
 [[package]]
 name = "syn"
 version = "1.0.109"
@@ -5934,6 +5945,7 @@ dependencies = [
  "scale-info",
  "subxt",
  "subxt-metadata",
+ "subxt-utils-stripmetadata",
  "trybuild",
 ]