BEEFY: implement equivocations detection, reporting and slashing (#13121)

* client/beefy: simplify self_vote logic

* client/beefy: migrate to new state version

* client/beefy: detect equivocated votes

* fix typos

* sp-beefy: add equivocation primitives

* client/beefy: refactor vote processing

* fix version migration for new rounds struct

* client/beefy: track equivocations and create proofs

* client/beefy: adjust tests for new voting logic

* sp-beefy: fix commitment ordering and equality

* client/beefy: simplify handle_vote() a bit

* client/beefy: add simple equivocation test

* client/beefy: submit equivocation proof - WIP

* frame/beefy: add equivocation report runtime api - part 1

* frame/beefy: report equivocation logic - part 2

* frame/beefy: add pluggable Equivocation handler - part 3

* frame/beefy: impl ValidateUnsigned for equivocations reporting

* client/beefy: submit report equivocation unsigned extrinsic

* primitives/beefy: fix tests

* frame/beefy: add default weights

* frame/beefy: fix tests

* client/beefy: fix tests

* frame/beefy-mmr: fix tests

* frame/beefy: cross-check session index with equivocation report

* sp-beefy: make test Keyring useable in pallet

* frame/beefy: add basic equivocation test

* frame/beefy: test verify equivocation results in slashing

* frame/beefy: test report_equivocation_old_set

* frame/beefy: add more equivocation tests

* sp-beefy: fix docs

* beefy: simplify equivocations and fix tests

* client/beefy: address review comments

* frame/beefy: add ValidateUnsigned to test/mock runtime

* client/beefy: fixes after merge master

* fix missed merge damage

* client/beefy: add test for reporting equivocations

Also validated there's no unexpected equivocations reported in the
other tests.

Signed-off-by: acatangiu <adrian@parity.io>

* sp-beefy: move test utils to their own file

* client/beefy: add negative test for equivocation reports

* sp-beefy: move back MmrRootProvider - used in polkadot-service

* impl review suggestions

* client/beefy: add equivocation metrics

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Signed-off-by: acatangiu <adrian@parity.io>
Co-authored-by: parity-processbot <>