Rococo/Westend Coretime Runtime

New runtimes for the Coretime Chain (a.k.a. "Broker Chain") described in
RFC-1.

Replaces https://github.com/paritytech/cumulus/pull/2889


- [x] Add Agile Coretime pallet
https://github.com/paritytech/substrate/pull/14568
- [x] Generate chain specs for local and testnets
- [x] Deploy parachain on Rococo - Done:
[rococo-coretime-rpc.polkadot.io](https://polkadot.js.org/apps/?rpc=wss%3A%2F%2Frococo-coretime-rpc.polkadot.io#/explorer)

DevOps issue for Aura keygen:
https://github.com/paritytech/devops/issues/2725

Edit (Dónal): This PR is mainly for Rococo, the Westend runtime is a
shell with no `Broker` pallet. The Rococo runtime has the broker calls
filtered for initial deployment.

---------

Co-authored-by: Dónal Murray <donal.murray@parity.io>
Co-authored-by: 0xmovses <r.v.melkonian@gmail.com>
Co-authored-by: Liam Aharon <liam.aharon@hotmail.com>
Co-authored-by: Bastian Köcher <git@kchr.de>
Co-authored-by: Marcin S. <marcin@realemail.net>
Co-authored-by: Bastian Köcher <info@kchr.de>
Co-authored-by: command-bot <>
Co-authored-by: Branislav Kontur <bkontur@gmail.com>

prdoc/pr_1479.prdoc

@@ -0,0 +1,11 @@
+# Schema: Polkadot SDK PRDoc Schema (prdoc) v1.0.0
+# See doc at https://raw.githubusercontent.com/paritytech/polkadot-sdk/master/prdoc/schema_user.json
+
+title: Rococo/Westend Coretime Runtime
+
+doc:
+  - audience: Runtime User
+    description: |
+      Rococo/Westend runtime for the Coretime Chain (a.k.a. "Broker Chain") described in RFC-1.
+
+crates: [ ]