Introduce cancel_proposal to rid us of those pesky proposals (#7111)

* Introduce `cancel_proposal`

Also fix proposal weight.

* Support proposal cancellation from runtime.

* Fixes

* Fixes

* Fixes

* Fixes

* Fixes

* Fixes

* Fixes

* Fix benchmarks

* fix benchmark

* whitelisted caller weights

* fix build

* Fixes

* Fixes

* Fixes

* Fixes

* Update frame/democracy/src/lib.rs

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>

* Fixes

* Fixes

* Fixes

* Fixes

* Fixes

* doc updates

* new weights

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>

substrate/bin/node/runtime/src/lib.rs

@@ -483,6 +483,7 @@ parameter_types! {
 	// One cent: $10,000 / MB
 	pub const PreimageByteDeposit: Balance = 1 * CENTS;
 	pub const MaxVotes: u32 = 100;
+	pub const MaxProposals: u32 = 100;
 }
 
 impl pallet_democracy::Trait for Runtime {
@@ -508,6 +509,14 @@ impl pallet_democracy::Trait for Runtime {
 	type FastTrackVotingPeriod = FastTrackVotingPeriod;
 	// To cancel a proposal which has been passed, 2/3 of the council must agree to it.
 	type CancellationOrigin = pallet_collective::EnsureProportionAtLeast<_2, _3, AccountId, CouncilCollective>;
+	// To cancel a proposal before it has been passed, the technical committee must be unanimous or
+	// Root must agree.
+	type CancelProposalOrigin = EnsureOneOf<
+		AccountId,
+		EnsureRoot<AccountId>,
+		pallet_collective::EnsureProportionAtLeast<_1, _1, AccountId, TechnicalCollective>,
+	>;
+	type BlacklistOrigin = EnsureRoot<AccountId>;
 	// Any single technical committee member may veto a coming council proposal, however they can
 	// only do it once and it lasts only for the cooloff period.
 	type VetoOrigin = pallet_collective::EnsureMember<AccountId, TechnicalCollective>;
@@ -519,6 +528,7 @@ impl pallet_democracy::Trait for Runtime {
 	type PalletsOrigin = OriginCaller;
 	type MaxVotes = MaxVotes;
 	type WeightInfo = weights::pallet_democracy::WeightInfo<Runtime>;
+	type MaxProposals = MaxProposals;
 }
 
 parameter_types! {