Changed (Vec2, Vec2) to Rect in Camera::logical_viewport_rect (#7867)

# Objective

`Camera::logical_viewport_rect()` returns `Option<(Vec2, Vec2)>` which
is a tuple of vectors representing the `(min, max)` bounds of the
viewport rect. Since the function says it returns a rect and there is a
`Rect { min, max }` struct in `bevy_math`, using the struct will be
clearer.

## Solution

Replaced `Option<(Vec2, Vec2)>` with `Option<Rect>` for
`Camera::logical_viewport_rect()`.

---

## Changelog

- Changed `Camera::logical_viewport_rect` return type from `(Vec2,
Vec2)` to `Rect`

## Migration Guide

Before:
```
fn view_logical_camera_rect(camera_query: Query<&Camera>) {
    let camera = camera_query.single();
    let Some((min, max)) = camera.logical_viewport_rect() else { return };
    dbg!(min, max);
}
```

After:
```
fn view_logical_camera_rect(camera_query: Query<&Camera>) {
    let camera = camera_query.single();
    let Some(Rect { min, max }) = camera.logical_viewport_rect() else { return };
    dbg!(min, max);
}
```

crates/bevy_render/src/camera/camera.rs

@@ -18,7 +18,7 @@ use bevy_ecs::{
     system::{Commands, Query, Res, ResMut, Resource},
 };
 use bevy_log::warn;
-use bevy_math::{Mat4, Ray, UVec2, UVec4, Vec2, Vec3};
+use bevy_math::{Mat4, Ray, Rect, UVec2, UVec4, Vec2, Vec3};
 use bevy_reflect::prelude::*;
 use bevy_reflect::FromReflect;
 use bevy_transform::components::GlobalTransform;
@@ -156,13 +156,16 @@ impl Camera {
         Some((min, max))
     }
 
-    /// The rendered logical bounds (minimum, maximum) of the camera. If the `viewport` field is set
-    /// to [`Some`], this will be the rect of that custom viewport. Otherwise it will default to the
+    /// The rendered logical bounds [`Rect`] of the camera. If the `viewport` field is set to
+    /// [`Some`], this will be the rect of that custom viewport. Otherwise it will default to the
     /// full logical rect of the current [`RenderTarget`].
     #[inline]
-    pub fn logical_viewport_rect(&self) -> Option<(Vec2, Vec2)> {
+    pub fn logical_viewport_rect(&self) -> Option<Rect> {
         let (min, max) = self.physical_viewport_rect()?;
-        Some((self.to_logical(min)?, self.to_logical(max)?))
+        Some(Rect {
+            min: self.to_logical(min)?,
+            max: self.to_logical(max)?,
+        })
     }
 
     /// The logical size of this camera's viewport. If the `viewport` field is set to [`Some`], this