thread local chain type vs global chain type (#3327)

* Introduce GLOBAL_CHAIN_TYPE and make CHAIN_TYPE thread_local.
This makes testing more explicit and significantly more robust.

* set_local_chain_type() in tests

* cleanup - weird

* get pool tests working with explicit local chain_type config

* core tests working with explicit local chain_type

* p2p tests working with explicit local chain_type

* store tests working

* cleanup, feedback

util/src/lib.rs

@@ -100,6 +100,11 @@ where
 			.clone()
 			.expect("Cannot borrow one_time before initialization.")
 	}
+
+	/// Has this OneTime been initialized?
+	pub fn is_init(&self) -> bool {
+		self.inner.read().is_some()
+	}
 }
 
 /// Encode an utf8 string to a base64 string