gpui: Add text alignment (#24090)

Adds a text property for controlling left, center, or right text
alignment.

#8792 should stay open since this doesn't add support for `justify`
(which would require a much bigger change since this can just alter the
origin of each line, but justify requires changing spacing, whereas
justify requires changes to each platform's shaping code).

Release Notes:

- N/A

crates/gpui/src/elements/div.rs

@@ -1661,6 +1661,8 @@ impl Interactivity {
         window: &mut Window,
         cx: &mut App,
     ) {
+        use crate::TextAlign;
+
         if global_id.is_some()
             && (style.debug || style.debug_below || cx.has_global::<crate::DebugBelow>())
             && hitbox.is_hovered(window)
@@ -1682,7 +1684,8 @@ impl Interactivity {
                     .ok()
                     .and_then(|mut text| text.pop())
                 {
-                    text.paint(hitbox.origin, FONT_SIZE, window, cx).ok();
+                    text.paint(hitbox.origin, FONT_SIZE, TextAlign::Left, window, cx)
+                        .ok();
 
                     let text_bounds = crate::Bounds {
                         origin: hitbox.origin,

crates/gpui/src/elements/text.rs

@@ -390,8 +390,10 @@ impl TextLayout {
 
         let line_height = element_state.line_height;
         let mut line_origin = bounds.origin;
+        let text_style = window.text_style();
         for line in &element_state.lines {
-            line.paint(line_origin, line_height, window, cx).log_err();
+            line.paint(line_origin, line_height, text_style.text_align, window, cx)
+                .log_err();
             line_origin.y += line.size(line_height).height;
         }
     }