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/integration-tests/emulated/networks/rococo-system/src/lib.rs

@@ -16,11 +16,13 @@
 pub use asset_hub_rococo_emulated_chain;
 pub use bridge_hub_rococo_emulated_chain;
 pub use penpal_emulated_chain;
+pub use people_rococo_emulated_chain;
 pub use rococo_emulated_chain;
 
 use asset_hub_rococo_emulated_chain::AssetHubRococo;
 use bridge_hub_rococo_emulated_chain::BridgeHubRococo;
 use penpal_emulated_chain::{PenpalA, PenpalB};
+use people_rococo_emulated_chain::PeopleRococo;
 use rococo_emulated_chain::Rococo;
 
 // Cumulus
@@ -37,6 +39,7 @@ decl_test_networks! {
 			BridgeHubRococo,
 			PenpalA,
 			PenpalB,
+			PeopleRococo,
 		],
 		bridge = ()
 	},
@@ -47,5 +50,6 @@ decl_test_sender_receiver_accounts_parameter_types! {
 	AssetHubRococoPara { sender: ALICE, receiver: BOB },
 	BridgeHubRococoPara { sender: ALICE, receiver: BOB },
 	PenpalAPara { sender: ALICE, receiver: BOB },
-	PenpalBPara { sender: ALICE, receiver: BOB }
+	PenpalBPara { sender: ALICE, receiver: BOB },
+	PeopleRococoPara { sender: ALICE, receiver: BOB }
 }