Added multi windows check for bevy_ui Interaction. (bevyengine#5225)

# Objective

- Currently bevy_ui only checks for primary window cursor position to determine `Interaction` behavior.
- Added checks for focused window where cursor position is available.
- Fixes bevyengine#5224.

## Solution

- Added checks for focused windows in `Interaction` focus system.

## Follow Up

- All windows with camera will be rendering the UI elements right now.
- We will need some way to tell which camera to render which UI.

---

Co-authored-by: fadhliazhari <44402264+fadhliazhari@users.noreply.github.com>

crates/bevy_ui/src/focus.rs

@@ -1,4 +1,4 @@
-use crate::{CalculatedClip, Node};
+use crate::{entity::UiCameraConfig, CalculatedClip, Node};
 use bevy_ecs::{
     entity::Entity,
     prelude::Component,
@@ -8,6 +8,7 @@ use bevy_ecs::{
 use bevy_input::{mouse::MouseButton, touch::Touches, Input};
 use bevy_math::Vec2;
 use bevy_reflect::{Reflect, ReflectDeserialize, ReflectSerialize};
+use bevy_render::camera::{Camera, RenderTarget};
 use bevy_transform::components::GlobalTransform;
 use bevy_utils::FloatOrd;
 use bevy_window::Windows;
@@ -52,6 +53,7 @@ pub struct State {
 /// The system that sets Interaction for all UI elements based on the mouse cursor activity
 pub fn ui_focus_system(
     mut state: Local<State>,
+    camera: Query<(&Camera, Option<&UiCameraConfig>)>,
     windows: Res<Windows>,
     mouse_button_input: Res<Input<MouseButton>>,
     touches_input: Res<Touches>,
@@ -88,9 +90,22 @@ pub fn ui_focus_system(
     let mouse_clicked =
         mouse_button_input.just_pressed(MouseButton::Left) || touches_input.any_just_pressed();
 
-    let cursor_position = windows
-        .get_primary()
-        .and_then(|window| window.cursor_position())
+    let is_ui_disabled =
+        |camera_ui| matches!(camera_ui, Some(&UiCameraConfig { show_ui: false, .. }));
+
+    let cursor_position = camera
+        .iter()
+        .filter(|(_, camera_ui)| !is_ui_disabled(*camera_ui))
+        .filter_map(|(camera, _)| {
+            if let RenderTarget::Window(window_id) = camera.target {
+                Some(window_id)
+            } else {
+                None
+            }
+        })
+        .filter_map(|window_id| windows.get(window_id))
+        .filter(|window| window.is_focused())
+        .find_map(|window| window.cursor_position())
         .or_else(|| touches_input.first_pressed_position());
 
     let mut moused_over_z_sorted_nodes = node_query