Move deprecated JitterBuffer to modules/video_coding/deprecated/

This move further clarifies that the file and its class are deprecated. It also cleans up the modules/video_coding root folder a bit.

No functional changes are intended.

Bug: webrtc:14876
Change-Id: Ic3ac439b3dd3492e6c9c85869efa80a6708658ee
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/301521
Reviewed-by: Philip Eliasson <philipel@webrtc.org>
Commit-Queue: Rasmus Brandt <brandtr@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#39876}
diff --git a/modules/video_coding/video_coding_impl.h b/modules/video_coding/video_coding_impl.h
index cd32330..de17033 100644
--- a/modules/video_coding/video_coding_impl.h
+++ b/modules/video_coding/video_coding_impl.h
@@ -20,9 +20,9 @@
 #include "api/field_trials_view.h"
 #include "api/sequence_checker.h"
 #include "modules/video_coding/deprecated/frame_buffer.h"
+#include "modules/video_coding/deprecated/jitter_buffer.h"
 #include "modules/video_coding/generic_decoder.h"
 #include "modules/video_coding/include/video_coding.h"
-#include "modules/video_coding/jitter_buffer.h"
 #include "modules/video_coding/receiver.h"
 #include "modules/video_coding/timing/timing.h"
 #include "rtc_base/one_time_event.h"