Remove deprecated mqtrigger with kind fission (#2875)

* Remove deprecated mqtrigger with kind fission
* Remove unused deps

---------

Signed-off-by: Sanket Sudake <sanketsudake@gmail.com>

pkg/mqtrigger/messageQueue.go

@@ -0,0 +1,30 @@
+/*
+Copyright 2020 The Fission Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package mqtrigger
+
+import (
+	fv1 "github.com/fission/fission/pkg/apis/core/v1"
+)
+
+type (
+	Subscription interface{}
+
+	MessageQueue interface {
+		Subscribe(trigger *fv1.MessageQueueTrigger) (Subscription, error)
+		Unsubscribe(triggerSub Subscription) error
+	}
+)