Add subxt feature in subxt-signer crate to default features (#1193)

* add subxt to subxt-signer default features

* distinguish between native and web in signer

* fix formatting and clippy

* rustfmt

testing/integration-tests/src/full_client/client/unstable_rpcs.rs

@@ -210,10 +210,7 @@ async fn chainhead_unstable_unpin() {
     };
     let sub_id = blocks.subscription_id().unwrap();
 
-    assert!(rpc
-        .chainhead_unstable_unpin(sub_id.clone(), hash)
-        .await
-        .is_ok());
+    assert!(rpc.chainhead_unstable_unpin(sub_id, hash).await.is_ok());
     // The block was already unpinned.
     assert!(rpc.chainhead_unstable_unpin(sub_id, hash).await.is_err());
 }