Make CreateWindowParams type and create_windows system public (#12428)

# Objective

To have a user level workaround for #12237.

## Solution

Workaround to the problem is described in:
https://github.com/bevyengine/bevy/issues/12237#issuecomment-1983680632

## Changelog

### Changed

- `CreateWindowParams` type and `create_windows` system from
`bevy_winit` is now public, which allows library authors and game
developers to manually trigger window creation when needed.

crates/bevy_winit/src/lib.rs

@@ -16,7 +16,8 @@ mod winit_windows;
 use approx::relative_eq;
 use bevy_a11y::AccessibilityRequested;
 use bevy_utils::Instant;
-use system::{changed_windows, create_windows, despawn_windows, CachedWindow};
+pub use system::create_windows;
+use system::{changed_windows, despawn_windows, CachedWindow};
 use winit::dpi::{LogicalSize, PhysicalSize};
 pub use winit_config::*;
 pub use winit_event::*;
@@ -232,7 +233,8 @@ impl Default for WinitAppRunnerState {
     }
 }
 
-type CreateWindowParams<'w, 's, F = ()> = (
+/// The parameters of the [`create_windows`] system.
+pub type CreateWindowParams<'w, 's, F = ()> = (
     Commands<'w, 's>,
     Query<'w, 's, (Entity, &'static mut Window), F>,
     EventWriter<'w, WindowCreated>,

crates/bevy_winit/src/system.rs

@@ -34,7 +34,7 @@ use crate::{
 /// If any of these entities are missing required components, those will be added with their
 /// default values.
 #[allow(clippy::too_many_arguments)]
-pub(crate) fn create_windows<F: QueryFilter + 'static>(
+pub fn create_windows<F: QueryFilter + 'static>(
     event_loop: &EventLoopWindowTarget<crate::UserEvent>,
     (
         mut commands,