Make VideoFrameType an enum class, and move to separate file and target

Bug: webrtc:5876, webrtc:6883
Change-Id: I1435cfa9e8e54c4ba2978261048ff3fbb993ce0e
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/126225
Commit-Queue: Niels Moller <nisse@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27239}
diff --git a/modules/video_coding/packet.cc b/modules/video_coding/packet.cc
index 5b826e8..5dd01e8 100644
--- a/modules/video_coding/packet.cc
+++ b/modules/video_coding/packet.cc
@@ -23,7 +23,7 @@
       sizeBytes(0),
       markerBit(false),
       timesNacked(-1),
-      frameType(kEmptyFrame),
+      frameType(VideoFrameType::kEmptyFrame),
       completeNALU(kNaluUnset),
       insertStartCode(false),
       video_header(),