Improve SignedExtension matching logic and remove SkipCheckIfFeeless bits (#1283)

* First pass making matching on signed exts more general and handlng SkipCheckifFeeless

* remove unneeded derives (only exts we can decode into are handled by the user)

* No SkipCheckIfFeeless in integration tests either

* Cargo fmt

* Remove SkipCheckIfFeeless specific logic

* clippy

* matches to just return bool, not result

* remove now-invalid comment

* return error from find if .iter() errors

subxt/src/config/default_extrinsic_params.rs

@@ -17,7 +17,6 @@ pub type DefaultExtrinsicParams<T> = signed_extensions::AnyOf<
         signed_extensions::CheckMortality<T>,
         signed_extensions::ChargeAssetTxPayment<T>,
         signed_extensions::ChargeTransactionPayment,
-        signed_extensions::SkipCheckIfFeeless<T, signed_extensions::ChargeAssetTxPayment<T>>,
     ),
 >;
 
@@ -132,9 +131,6 @@ impl<T: Config> DefaultExtrinsicParamsBuilder<T> {
         let charge_transaction_params =
             signed_extensions::ChargeTransactionPaymentParams::tip(self.tip);
 
-        let skip_check_params =
-            signed_extensions::SkipCheckIfFeelessParams::from(charge_asset_tx_params.clone());
-
         (
             (),
             (),
@@ -143,7 +139,6 @@ impl<T: Config> DefaultExtrinsicParamsBuilder<T> {
             check_mortality_params,
             charge_asset_tx_params,
             charge_transaction_params,
-            skip_check_params,
         )
     }
 }