Adding PartialEq to some UI and Text types (#19552)

# Objective

- During the development of
[`bevy_flair`](https://github.com/eckz/bevy_flair) I found [some types
lacking
`PartialEq`](https://github.com/search?q=repo%3Aeckz%2Fbevy_flair%20%20%22Try%20to%20upstream%20it%20to%20bevy%22&type=code)
which made the unit testing a little bit inconvinient.

## Solution

- Adding `PartialEq` for the following types:
  - `LineHeight `
  - `TextShadow`
  - `NodeImageMode`

## Testing

- Letting github actions do the testing, this is not an invasive change
and `cargo run --bin ci` doesn't seem to work in `main` at the moment.

crates/bevy_text/src/text.rs

@@ -354,8 +354,8 @@ impl Default for TextFont {
 /// Specifies the height of each line of text for `Text` and `Text2d`
 ///
 /// Default is 1.2x the font size
-#[derive(Debug, Clone, Copy, Reflect)]
-#[reflect(Debug, Clone)]
+#[derive(Debug, Clone, Copy, PartialEq, Reflect)]
+#[reflect(Debug, Clone, PartialEq)]
 pub enum LineHeight {
     /// Set line height to a specific number of pixels
     Px(f32),

crates/bevy_ui/src/ui_node.rs

@@ -2865,8 +2865,8 @@ impl ComputedNodeTarget {
 }
 
 /// Adds a shadow behind text
-#[derive(Component, Copy, Clone, Debug, Reflect)]
-#[reflect(Component, Default, Debug, Clone)]
+#[derive(Component, Copy, Clone, Debug, PartialEq, Reflect)]
+#[reflect(Component, Default, Debug, Clone, PartialEq)]
 pub struct TextShadow {
     /// Shadow displacement in logical pixels
     /// With a value of zero the shadow will be hidden directly behind the text

crates/bevy_ui/src/widget/image.rs

@@ -138,8 +138,8 @@ impl From<Handle<Image>> for ImageNode {
 }
 
 /// Controls how the image is altered to fit within the layout and how the layout algorithm determines the space in the layout for the image
-#[derive(Default, Debug, Clone, Reflect)]
-#[reflect(Clone, Default)]
+#[derive(Default, Debug, Clone, PartialEq, Reflect)]
+#[reflect(Clone, Default, PartialEq)]
 pub enum NodeImageMode {
     /// The image will be sized automatically by taking the size of the source image and applying any layout constraints.
     #[default]