Implement character index for point (#23989)

Fixes #22939
Fixes #23970
Supersedes https://github.com/zed-industries/zed/pull/23469

Release Notes:

- Fixed a bug where Zed could crash with certain input sources on macOS

---------

Co-authored-by: Louis Brunner <louis.brunner.fr@gmail.com>
Co-authored-by: ben <ben@zed.dev>

crates/gpui/src/geometry.rs

@@ -217,6 +217,19 @@ impl Point<Pixels> {
     }
 }
 
+impl<T> Point<T>
+where
+    T: Sub<T, Output = T> + Debug + Clone + Default,
+{
+    /// Get the position of this point, relative to the given origin
+    pub fn relative_to(&self, origin: &Point<T>) -> Point<T> {
+        point(
+            self.x.clone() - origin.x.clone(),
+            self.y.clone() - origin.y.clone(),
+        )
+    }
+}
+
 impl<T, Rhs> Mul<Rhs> for Point<T>
 where
     T: Mul<Rhs, Output = T> + Clone + Default + Debug,
@@ -376,6 +389,13 @@ pub struct Size<T: Clone + Default + Debug> {
     pub height: T,
 }
 
+impl<T: Clone + Default + Debug> Size<T> {
+    /// Create a new Size, a synonym for [`size`]
+    pub fn new(width: T, height: T) -> Self {
+        size(width, height)
+    }
+}
+
 /// Constructs a new `Size<T>` with the provided width and height.
 ///
 /// # Arguments
@@ -1456,6 +1476,17 @@ where
     }
 }
 
+impl<T> Bounds<T>
+where
+    T: Add<T, Output = T> + PartialOrd + Clone + Default + Debug + Sub<T, Output = T>,
+{
+    /// Convert a point to the coordinate space defined by this Bounds
+    pub fn localize(&self, point: &Point<T>) -> Option<Point<T>> {
+        self.contains(point)
+            .then(|| point.relative_to(&self.origin))
+    }
+}
+
 /// Checks if the bounds represent an empty area.
 ///
 /// # Returns