new variables for global state

src/singletons/global_state.gd

@@ -3,8 +3,11 @@ extends Node
 var screen_reader:bool = false
 var disable_rendering: bool = false
 var simplified_navigation:bool = false
+var show_navigation_buttons: bool = false
 var enable_subtitles: bool = false
+var enable_closed_caption: bool = false
 var reduce_motion: bool = false
+var streaming_content_notes: bool = false
 var show_content_notes: bool = false
 var provide_summaries: bool = false
 var allow_skipping: bool = false