babe: report equivocations (#6362)

* slots: create primitives crate for consensus slots

* offences: add method to check if an offence is unknown

* babe: initial equivocation reporting implementation

* babe: organize imports

* babe: working equivocation reporting

* babe: add slot number to equivocation proof

* session: move duplicate traits to session primitives

* babe: move equivocation stuff to its own file

* offences: fix test

* session: don't have primitives depend on frame_support

* babe: use opaque type for key owner proof

* babe: cleanup client equivocation reporting

* babe: cleanup equivocation code in pallet

* babe: allow sending signed equivocation reports

* node: fix compilation

* fix test compilation

* babe: return bool on check_equivocation_proof

* babe: add test for equivocation reporting

* babe: add more tests

* babe: add test for validate unsigned

* babe: take slot number in generate_key_ownership_proof API

* babe: add benchmark for equivocation proof checking

* session: add benchmark for membership proof checking

* offences: fix babe benchmark

* babe: add weights based on benchmark results

* babe: adjust weights after benchmarking on reference hardware

* babe: reorder checks in check_and_report_equivocation

substrate/Cargo.lock

@@ -4009,9 +4009,15 @@ dependencies = [
 name = "pallet-babe"
 version = "2.0.0-rc4"
 dependencies = [
+ "frame-benchmarking",
  "frame-support",
  "frame-system",
+ "pallet-authorship",
+ "pallet-balances",
+ "pallet-offences",
  "pallet-session",
+ "pallet-staking",
+ "pallet-staking-reward-curve",
  "pallet-timestamp",
  "parity-scale-codec",
  "serde",
@@ -4022,6 +4028,7 @@ dependencies = [
  "sp-inherents",
  "sp-io",
  "sp-runtime",
+ "sp-session",
  "sp-staking",
  "sp-std",
  "sp-timestamp",
@@ -4554,10 +4561,12 @@ dependencies = [
  "pallet-staking-reward-curve",
  "pallet-timestamp",
  "parity-scale-codec",
+ "rand 0.7.3",
  "serde",
  "sp-core",
  "sp-io",
  "sp-runtime",
+ "sp-session",
  "sp-std",
 ]
 
@@ -6343,6 +6352,7 @@ dependencies = [
  "sp-application-crypto",
  "sp-blockchain",
  "sp-consensus",
+ "sp-consensus-slots",
  "sp-core",
  "sp-inherents",
  "sp-runtime",
@@ -7568,6 +7578,7 @@ dependencies = [
  "sp-api",
  "sp-application-crypto",
  "sp-consensus",
+ "sp-consensus-slots",
  "sp-consensus-vrf",
  "sp-core",
  "sp-inherents",
@@ -7587,6 +7598,14 @@ dependencies = [
  "sp-std",
 ]
 
+[[package]]
+name = "sp-consensus-slots"
+version = "0.8.0-rc4"
+dependencies = [
+ "parity-scale-codec",
+ "sp-runtime",
+]
+
 [[package]]
 name = "sp-consensus-vrf"
 version = "0.8.0-rc4"