Disputes runtime (#2947)

* disputes module skeleton and storage

* implement dispute module initialization logic

* implement disputes session change logic

* provide dispute skeletons

* deduplication & ancient check

* fix a couple of warnings

* begin provide_dispute_data impl

* flesh out statement set import somewhat

* move ApprovalVote to shared primitives

* add a signing-payload API to explicit dispute statements

* implement statement signature checking

* some bitflags glue for observing changes in disputes

* implement dispute vote import logic

* flesh out everything except slashing

* guide: tweaks

* declare and use punishment trait

* punish validators for inconclusive disputes

* guide: tiny fix

* guide: update docs

* add disputes getter fn

* guide: small change to spam slots handling

* improve spam slots handling and fix some bugs

* finish API of disputes runtime

* define and deposit `RevertTo` log

* begin integrating disputes into para_inherent

* use precomputed slash_for/against

* return candidate hash from process_bitfields

* implement inclusion::collect_disputed

* finish integration into rest of runtime

* add Disputes to initializer

* address suggestions

* use pallet macro

* fix typo

* Update runtime/parachains/src/disputes.rs

* add test: fix pruning

* document specific behavior

* deposit events on dispute changes

* add an allow(unused) on fn disputes

* add a dummy PunishValidators implementation

* add disputes module to Rococo

* add disputes module to westend runtime

* add disputes module to test runtime

* add disputes module to kusama runtime

* guide: prepare for runtime API for checking frozenness

* remove revert digests in favor of state variable

* merge reversions

* Update runtime/parachains/src/disputes.rs

Co-authored-by: André Silva <[email protected]>

* Update runtime/parachains/src/disputes.rs

Co-authored-by: André Silva <[email protected]>

* Update runtime/parachains/src/disputes.rs

Co-authored-by: André Silva <[email protected]>

* add byzantine_threshold and supermajority_threshold utilities to primitives

* use primitive helpers

* deposit revert event when freezing chain

* deposit revert log when freezing chain

* test revert event and log are generated when freezing

* add trait to decouple disputes handling from paras inherent handling

* runtime: fix compilation and setup dispute handler

* disputes: add hook for filtering out dispute statements

* disputes: add initializer hooks to DisputesHandler

* runtime: remove disputes pallet from all runtimes

* tag TODOs

* don't import any dispute statements just yet...

* address grumbles

* fix spellcheck, hopefully

* maybe now?

* last spellcheck round

* fix runtime tests

* fix test-runtime

Co-authored-by: thiolliere <[email protected]>
Co-authored-by: André Silva <[email protected]>
Co-authored-by: André Silva <[email protected]>