bevy_input_focus improvements (follow-up PR) (#16665)

This adds a few minor items which were left out of the previous PR:

- Added synchronization from bevy_input_focus to bevy_a11y.
- Initialize InputFocusVisible resource.
- Make `input_focus` available from `bevy` module.

I've tested this using VoiceOver on Mac OS. It works, but it needs
considerable polish.

crates/bevy_input_focus/src/lib.rs

@@ -107,6 +107,7 @@ pub struct InputDispatchPlugin;
 impl Plugin for InputDispatchPlugin {
     fn build(&self, app: &mut App) {
         app.insert_resource(InputFocus(None))
+            .insert_resource(InputFocusVisible(false))
             .add_systems(Update, dispatch_keyboard_input);
     }
 }

crates/bevy_internal/Cargo.toml

@@ -268,6 +268,7 @@ bevy_ecs = { path = "../bevy_ecs", version = "0.15.0-dev" }
 bevy_state = { path = "../bevy_state", optional = true, version = "0.15.0-dev" }
 bevy_hierarchy = { path = "../bevy_hierarchy", version = "0.15.0-dev" }
 bevy_input = { path = "../bevy_input", version = "0.15.0-dev" }
+bevy_input_focus = { path = "../bevy_input_focus", version = "0.15.0-dev" }
 bevy_log = { path = "../bevy_log", version = "0.15.0-dev" }
 bevy_math = { path = "../bevy_math", version = "0.15.0-dev" }
 bevy_ptr = { path = "../bevy_ptr", version = "0.15.0-dev" }

crates/bevy_internal/src/lib.rs

@@ -41,6 +41,7 @@ pub use bevy_hierarchy as hierarchy;
 #[cfg(feature = "bevy_image")]
 pub use bevy_image as image;
 pub use bevy_input as input;
+pub use bevy_input_focus as input_focus;
 pub use bevy_log as log;
 pub use bevy_math as math;
 #[cfg(feature = "bevy_pbr")]