Nomination pool configurations can be managed by custom origin (#3959)

closes https://github.com/paritytech/polkadot-sdk/issues/3894

Allows Nomination Pool configuration to be set by a custom origin
instead of root.

In runtimes, we would set this to be `StakingAdmin`, same as for
pallet-staking.

---------

Co-authored-by: Liam Aharon <liam.aharon@hotmail.com>

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

@@ -917,6 +917,10 @@ impl pallet_nomination_pools::Config for Runtime {
 	type MaxUnbonding = ConstU32<8>;
 	type PalletId = NominationPoolsPalletId;
 	type MaxPointsToBalance = MaxPointsToBalance;
+	type AdminOrigin = EitherOfDiverse<
+		EnsureRoot<AccountId>,
+		pallet_collective::EnsureProportionAtLeast<AccountId, CouncilCollective, 3, 4>,
+	>;
 }
 
 parameter_types! {