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

subxt/Cargo.toml

@@ -103,7 +103,7 @@ sp-core = { workspace = true }
 sp-keyring = { workspace = true }
 sp-runtime = { workspace = true }
 assert_matches = { workspace = true }
-subxt-signer = { path = "../signer", features = ["subxt"] }
+subxt-signer = { path = "../signer" }
 # Tracing subscriber is useful for light-client examples to ensure that
 # the `bootNodes` and chain spec are configured correctly. If all is fine, then
 # the light-client wlll emit INFO logs with