rpc: add rpc v2 chainSpec to polkadot (#2859)

The [chainSpec RPC API from the v2
spec](https://paritytech.github.io/json-rpc-interface-spec/api/chainSpec.html)
was only added to substrate-node and should be added to polkadot as well

/cc @lexnv

substrate/frame/support/procedural/src/construct_runtime/expand/task.rs

@@ -31,7 +31,7 @@ pub fn expand_outer_task(
 	let mut task_paths = Vec::new();
 	for decl in pallet_decls {
 		if decl.find_part("Task").is_none() {
-			continue;
+			continue
 		}
 
 		let variant_name = &decl.name;