Hide description header in tvOS video info right column

The right column is already dedicated to video info so the "Description"
label is redundant. Add an opt-out `showsHeader` parameter to
`TVScrollableDescription` (default true) and pass false from
`VideoInfoView`; the player overlay and channel view keep the header.

Yattee/Views/Video/VideoInfoView.swift

@@ -675,7 +675,8 @@ struct VideoInfoView: View {
                     } else if let description = displayedVideo?.description, !description.isEmpty {
                         TVScrollableDescription(
                             description: description,
-                            isScrollLocked: $isDescriptionScrollLocked
+                            isScrollLocked: $isDescriptionScrollLocked,
+                            showsHeader: false
                         )
                         .frame(height: isDescriptionScrollLocked ? geometry.size.height : 450)
                         .padding(.horizontal)