Connection quality clean up (#766)

* WIP commit

* WIP commit

* Remove debug

* Revert to reduce diff

* Fix tests

* Determine spatial layer from track info quality if non-simulcast

* Adjust for invalid layer on no rid, previously that function was returning 0 for no rid case

* Fall back to top level width/height if there are no layers

* Use duration from RTPDeltaInfo

pkg/sfu/buffer/streamstats.go

@@ -1,18 +1,6 @@
 package buffer
 
-type LayerStats struct {
-	Packets uint32
-	Bytes   uint64
-	Frames  uint32
-}
-
 type StreamStatsWithLayers struct {
 	RTPStats *RTPDeltaInfo
-	Layers   map[int]LayerStats
-}
-
-type ConnectionQualityParams struct {
-	LossPercentage float32
-	Jitter         float32
-	Rtt            uint32
+	Layers   map[int32]*RTPDeltaInfo
 }