move fetch metadata to a separate crate subxt_utils_fetchmetadata (#1829)

* macros: feature-gate jsonrpsee/fetch metadata url

* make CI happy

* Update codegen/src/error.rs

* extract `fetch-metdata` to separate crate

* add missing license headers

* introduce subxt-utils crate

* add missing files

* codegen: remove unused hex crate

* fix test build

* move subxt_utils -> subxt_utils_fetchmetadata

* cargo fmt

* runtime-path -> runtime-metadata-path

* Update utils/fetch-metadata/src/lib.rs

utils/fetch-metadata/src/lib.rs

@@ -0,0 +1,28 @@
+// Copyright 2019-2024 Parity Technologies (UK) Ltd.
+// This file is dual-licensed as Apache-2.0 or GPL-3.0.
+// see LICENSE for license details.
+
+//! Subxt utils fetch metadata.
+
+// Internal helper macros
+#[macro_use]
+mod macros;
+mod error;
+
+cfg_fetch_from_url! {
+    mod url;
+    pub use url::{from_url, from_url_blocking, MetadataVersion, Url};
+}
+
+pub use error::Error;
+
+/// Fetch metadata from a file in a blocking manner.
+pub fn from_file_blocking(path: &std::path::Path) -> Result<Vec<u8>, error::Error> {
+    use std::io::Read;
+
+    let to_err = |err| error::Error::Io(path.to_string_lossy().into(), err);
+    let mut file = std::fs::File::open(path).map_err(to_err)?;
+    let mut bytes = Vec::new();
+    file.read_to_end(&mut bytes).map_err(to_err)?;
+    Ok(bytes)
+}