Use native video call picture in picture! (#3190)

* Use native video call picture in picture!

* Handle isSupported, isPossible and web view errors.

* Use new canEnterPip method.

* Hide a room's Call button when already joined to the call.

* Tweak feature flag description.

* PR comments.

ElementX/Sources/Other/Extensions/UIView.swift

@@ -0,0 +1,30 @@
+//
+// Copyright 2024 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 SwiftUI
+
+extension UIView {
+    func addMatchedSubview(_ subview: UIView) {
+        addSubview(subview)
+        subview.translatesAutoresizingMaskIntoConstraints = false
+        NSLayoutConstraint.activate([
+            subview.topAnchor.constraint(equalTo: topAnchor),
+            subview.leadingAnchor.constraint(equalTo: leadingAnchor),
+            subview.trailingAnchor.constraint(equalTo: trailingAnchor),
+            subview.bottomAnchor.constraint(equalTo: bottomAnchor)
+        ])
+    }
+}