Session Delayed Para Changes / Actions Queue (#2406)

* initial implementation of lifecycles and upgrades

* clean up a bit

* fix doc comment

* more rigid lifecycle checks

* include paras which are transitioning, and lifecycle query

* format guide

* update api

* update guide

* explicit outgoing state, fix genesis

* handle outgoing with transitioning paras

* do not include transitioning paras in identifier

* Update roadmap/implementers-guide/src/runtime/paras.md

* Update roadmap/implementers-guide/src/runtime/paras.md

* Update roadmap/implementers-guide/src/runtime/paras.md

* Apply suggestions from code review

* Use matches macro

* Correct terms

* Apply suggestions from code review

* actions queue

* Revert "actions queue"

This reverts commit b2e9011e.

* collapse onboarding state

* starting actions queue

* consolidate actions queue

* schedule para initialize result

* more actions queue for upgrade/downgrade

* clean up with fully implemented actions queue

* fix tests

* fix scheduler tests

* fix hrmp tests

* fix test

* doc fixes

* fix hrmp test w/ valid para

* Update paras.md

* fix paras registrar

* Update propose_parachain.rs

* fix merge

* Introduce "shared" module

* fix rococo build

* fix up and use shared

* guide updates

* add shared config to common tests

* add shared to test-runtime

* remove println

* fix note

Co-authored-by: Gavin Wood <gavin@parity.io>
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