Rococo & Westend People Chain (#2281)

Rococo and Westend runtimes for the "People Chain". This chain contains
the Identity pallet with plans to migrate all related data from the
Relay Chain.

Changes `IdentityInfo` to:

- Remove `additional_fields`.
- Add `github` and `discord` as first class fields. From scraping chain
data, these were the only two additional fields used (for the Fellowship
and Ambassador Program, respectively).
- Rename `riot` to `matrix`.

Note: This will use the script in
https://github.com/paritytech/polkadot-sdk/pull/2025 to generate the
genesis state.

TODO:

- [x] https://github.com/paritytech/polkadot-sdk/pull/1814 and
integration of the Identity Migrator pallet for migration.
- [x] Tests: https://github.com/paritytech/polkadot-sdk/pull/2373

---------

Co-authored-by: Muharem <ismailov.m.h@gmail.com>
Co-authored-by: Michal Kucharczyk <1728078+michalkucharczyk@users.noreply.github.com>
Co-authored-by: Dónal Murray <donal.murray@parity.io>
Co-authored-by: Richard Melkonian <35300528+0xmovses@users.noreply.github.com>
Co-authored-by: Liam Aharon <liam.aharon@hotmail.com>

cumulus/parachains/runtimes/people/people-rococo/build.rs

@@ -0,0 +1,26 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#[cfg(feature = "std")]
+fn main() {
+	substrate_wasm_builder::WasmBuilder::new()
+		.with_current_project()
+		.export_heap_base()
+		.import_memory()
+		.build()
+}
+
+#[cfg(not(feature = "std"))]
+fn main() {}