move examples to main repo so we can include_str them for publishing (#993)

* move exampels to main repo so we can include_str them for publishing

* update CI to not break examples

subxt/examples/setup_client_offline.rs

@@ -0,0 +1,35 @@
+use subxt::ext::codec::Decode;
+use subxt::metadata::Metadata;
+use subxt::utils::H256;
+use subxt::{config::PolkadotConfig, OfflineClient};
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    // We need to obtain the following details for an OfflineClient to be instantiated:
+
+    // 1. Genesis hash (RPC call: chain_getBlockHash(0)):
+    let genesis_hash = {
+        let h = "91b171bb158e2d3848fa23a9f1c25182fb8e20313b2c1eb49219da7a70ce90c3";
+        let bytes = hex::decode(h).unwrap();
+        H256::from_slice(&bytes)
+    };
+
+    // 2. A runtime version (system_version constant on a Substrate node has these):
+    let runtime_version = subxt::rpc::types::RuntimeVersion {
+        spec_version: 9370,
+        transaction_version: 20,
+        other: Default::default(),
+    };
+
+    // 3. Metadata (I'll load it from the downloaded metadata, but you can use
+    //    `subxt metadata > file.scale` to download it):
+    let metadata = {
+        let bytes = std::fs::read("./artifacts/polkadot_metadata_small.scale").unwrap();
+        Metadata::decode(&mut &*bytes).unwrap()
+    };
+
+    // Create an offline client using the details obtained above:
+    let _api = OfflineClient::<PolkadotConfig>::new(genesis_hash, runtime_version, metadata);
+
+    Ok(())
+}