Render the macOS control bar button row and top bar from the active
preset's sections via a new MacOSControlsSectionRenderer, replacing the
hardcoded QuickTime-style rows in MacOSControlBar. Add a keepOnTop
button type and macOS-specific button availability lists, and adapt the
player controls settings editors (preset editor, section editor, button
configuration) for macOS.
Also apply the preset font style to the control bar time labels, and
update the built-in macOS Default preset order (queue before transport,
fullscreen at the end), bumping builtInPresetsVersion to 7.
On tvOS, ContentUnavailableView inside a Group doesn't expand to fill
available space — it sizes to content and aligns top-leading. Add
.frame(maxWidth: .infinity, maxHeight: .infinity) to all instances
so they center correctly in their parent containers.
