Present view options and search filters as popovers on macOS

Plain-Form sheets rendered as columns-style content floating inside
oversized fixed frames on macOS. Anchor these panels to their toolbar
buttons as popovers instead, sized to content; iOS/tvOS keep sheets.

- Search and PeerTube explore filters apply live (Cancel never
  reverted anything anyway) and dismiss on outside click
- Subscriptions/Manage Channels "Subscriptions Data" opens as a sheet
  from the popover's onDisappear via a pending flag, since presenting
  while the popover dismisses gets swallowed
- Media browser view options drop navigation chrome on macOS

Yattee/Views/Components/ViewOptionsSheet.swift

@@ -156,7 +156,8 @@ struct ViewOptionsSheet: View {
         .presentationDragIndicator(.visible)
         #endif
         #if os(macOS)
-        .frame(minWidth: 420, minHeight: 320)
+        .padding()
+        .frame(width: 300)
         #endif
     }
 }