Added OnResolutionChange to EncoderSelectorInterface.

Bug: webrtc:12406
Change-Id: I0160636d93ad0a33caf7ae7443cefe321a191406
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/258442
Reviewed-by: Sergey Silkin <ssilkin@webrtc.org>
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Commit-Queue: Philip Eliasson <philipel@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#36517}

test/video_encoder_proxy_factory.h

@@ -132,6 +132,11 @@ class VideoEncoderProxyFactory : public VideoEncoderFactory {
       return encoder_selector_->OnAvailableBitrate(rate);
     }
 
+    absl::optional<SdpVideoFormat> OnResolutionChange(
+        const RenderResolution& resolution) override {
+      return encoder_selector_->OnResolutionChange(resolution);
+    }
+
     absl::optional<SdpVideoFormat> OnEncoderBroken() override {
       return encoder_selector_->OnEncoderBroken();
     }