Signature Aggregation Refactor (#883)

* remove unused code

* remove signature aggregation job

* appease linter

* remove signature aggregation job

* move all signature aggregeation logic to AggregateSignatures

* nit

* nit

* nit

* add mock and tests

* clean up tests

* nit

* don't autogen SignatureGetter because it requires manual changes because gomock is broken

* nit

* comment

* comments

* lower log level

* re-add todo

* nit

* refactor aggregeateSignatures

* comment nits

* add tests

* use error from avalancheWap; combine functions; nits

* add logs

* typo fix

plugin/evm/vm.go

@@ -943,7 +943,7 @@ func (vm *VM) CreateHandlers(context.Context) (map[string]*commonEng.HTTPHandler
 	}
 
 	if vm.config.WarpAPIEnabled {
-		warpAggregator := aggregator.NewAggregator(vm.ctx.SubnetID, warpValidators.NewState(vm.ctx), &aggregator.NetworkSigner{Client: vm.client})
+		warpAggregator := aggregator.New(vm.ctx.SubnetID, warpValidators.NewState(vm.ctx), &aggregator.NetworkSigner{Client: vm.client})
 		if err := handler.RegisterName("warp", warp.NewAPI(vm.warpBackend, warpAggregator)); err != nil {
 			return nil, err
 		}