Move rtp-specific config out of EncoderSettings.

In VideoSendStream::Config, move payload_name and payload_type from
EncoderSettings to Rtp.

EncoderSettings now contains configuration for VideoStreamEncoder only,
and should perhaps be renamed in a follow up cl. It's no longer
passed as an argument to VideoCodecInitializer::SetupCodec.

The latter then needs a different way to know the codec type,
which is provided by a new codec_type member in VideoEncoderConfig.

Bug: webrtc:8830
Change-Id: Ifcc691aef1ee6a95e43c0452c5e630d92a511cd6
Reviewed-on: https://webrtc-review.googlesource.com/62062
Commit-Queue: Niels Moller <nisse@webrtc.org>
Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Reviewed-by: Rasmus Brandt <brandtr@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22532}

video/video_stream_encoder.cc

@@ -552,9 +552,8 @@ void VideoStreamEncoder::ReconfigureEncoder() {
   crop_height_ = last_frame_info_->height - highest_stream_height;
 
   VideoCodec codec;
-  if (!VideoCodecInitializer::SetupCodec(encoder_config_, settings_, streams,
-                                         nack_enabled_, &codec,
-                                         &rate_allocator_)) {
+  if (!VideoCodecInitializer::SetupCodec(
+          encoder_config_, streams, nack_enabled_, &codec, &rate_allocator_)) {
     RTC_LOG(LS_ERROR) << "Failed to create encoder configuration.";
   }