* scheduler module skeleton

* update scheduler skeleton to match latest version of guide

* better session change notification

* add mock randomness and fix test compilation

* shuffle validators into groups

* finish implementing session change logic for scheduler

* tweak core assignment type to track retries of parathread

* reframe queued parathread core as offset

* implement initialzation and finalization routines

* implement parathread claim queuing

* implement core_para

* implement the group_validators routine and fix errors

* add a reason for freeing cores

* implement `schedule` function

* add some docs to the scheduled function

* implement `occupied` helper

* implement availability predicate

* fix some warnings

* integrate scheduler into initializer

* integrate scheduler into mock module

* avoid conflict with Substrate's scheduler storage

* add parathreads index to paras module

* implement parathreads map in paras module

* add is_parathread to paras

* test adding parathread claim

* test that you cannot add claims when no parathread cores exist

* check session change parathread queue pruning

* test validator shuffling

* add allow_unused to scheduler items

* add test for scheduling

* add some more tests for scheduling logic

* test core rotation

* check parathread claim pruning after retries

* add bound notes

* Apply suggestions from code review

Co-authored-by: Peter Goodspeed-Niklaus <[email protected]>
Co-authored-by: Bernhard Schuster <[email protected]>

* more suggestions from review

* test availability predicate, add box to please compiler

* add changes to guide

Co-authored-by: Peter Goodspeed-Niklaus <[email protected]>
Co-authored-by: Bernhard Schuster <[email protected]>

* file structure and initializer skeleton

* ensure session changes happen before initialization

* add a couple tests for initializer flow

* integrate with session handling

* configuration update logic

* configuration methods

* move test mock to its own module

* integrate configuration into initializer

* add note about initialization order

* integrate configuration module into mock

* add some tests for config module

* paras module storage

* implement paras session change operation

* amend past code pruning to fully cover acceptance period

* update guide again

* do pruning of historical validation code

* add weight to initialization

* integrate into mock & leave notes for next session

* clean up un-ended sentence

* alter test to account for double index in past code meta

* port over code-at logic test

* clarify checking for conflicting code upgrades

* add genesis for paras, include in mock, ensure incoming paras are processed

* note on return value of `validation_code_at`

* implement paras routines from implementor's guide

* bring over some existing tests and begin porting

* port over code upgrade tests

* test parachain registration

* test code_at with intermediate block

* fix warnings

* clean up docs and extract to separate struct

* adjust implementor's guide to include replacementtimes

* kill stray println

* rename expected_at to applied_after

* rewrite ParaPastCodeMeta to avoid reversal

* clarify and test interface of validation_code_at

* make FutureCode optional

* rename do_old_code_pruning

* add comment on Option<()> to answer FAQ

* address some more grumbles