Add multipleTouchEnabled for subview of RTCMTLVideoView and RTCEAGLVideoView

Bug: webrtc:11044
Change-Id: Ice4232d54d4680b3228295ef8053e405cd0fa786
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/157980
Reviewed-by: Peter Hanspers <peterhanspers@webrtc.org>
Commit-Queue: Kári Helgason <kthelgason@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29583}

sdk/objc/components/renderer/metal/RTCMTLVideoView.m

@@ -119,6 +119,11 @@
   self.videoFrameSize = CGSizeZero;
 }
 
+- (void)setMultipleTouchEnabled:(BOOL)multipleTouchEnabled {
+    [super setMultipleTouchEnabled:multipleTouchEnabled];
+    self.metalView.multipleTouchEnabled = multipleTouchEnabled;
+}
+
 - (void)layoutSubviews {
   [super layoutSubviews];
 

sdk/objc/components/renderer/opengl/RTCEAGLVideoView.m

@@ -137,6 +137,11 @@
   return YES;
 }
 
+- (void)setMultipleTouchEnabled:(BOOL)multipleTouchEnabled {
+    [super setMultipleTouchEnabled:multipleTouchEnabled];
+    _glkView.multipleTouchEnabled = multipleTouchEnabled;
+}
+
 - (void)dealloc {
   [[NSNotificationCenter defaultCenter] removeObserver:self];
   UIApplicationState appState =