Replace user indicator presenting view controller with context

CommonKit/Source/UserIndicators/UserIndicatorViewPresentable.swift

@@ -0,0 +1,26 @@
+// 
+// Copyright 2021 New Vector Ltd
+//
+// 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.
+//
+
+import Foundation
+
+/// A presenter associated with and called by a `UserIndicator`, and responsible for the underlying view shown on the screen.
+public protocol UserIndicatorViewPresentable {
+    /// Called when the `UserIndicator` is started (manually or by the `UserIndicatorQueue`)
+    func present()
+    /// Called when the `UserIndicator` is manually cancelled or completed
+    func dismiss()
+}
+