Add new RPC method to get the chain type (#5576)

* Add new RPC method to get the chain type

This adds a new RPC method to get the chain type of the running chain.
The chain type needs to be specified in the chain spec. This should make
it easier for tools/UI to display extra information without needing to
rely on parsing the chain name.

* Update client/rpc-api/src/system/mod.rs

Co-Authored-By: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

* Primitive crate

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Co-authored-by: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

substrate/primitives/chain-spec/src/lib.rs

@@ -0,0 +1,42 @@
+// Copyright 2020 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Types and traits related to chain specifications.
+
+/// The type of a chain.
+///
+/// This can be used by tools to determine the type of a chain for displaying
+/// additional information or enabling additional features.
+#[derive(serde::Serialize, serde::Deserialize, Debug, PartialEq, Clone)]
+pub enum ChainType {
+	/// A development chain that runs mainly on one node.
+	Development,
+	/// A local chain that runs locally on multiple nodes for testing purposes.
+	Local,
+	/// A live chain.
+	Live,
+	/// Some custom chain type.
+	Custom(String),
+}
+
+impl Default for ChainType {
+	fn default() -> Self {
+		Self::Live
+	}
+}
+
+/// Arbitrary properties defined in chain spec as a JSON object
+pub type Properties = serde_json::map::Map<String, serde_json::Value>;