Preserve cursor position when resetting excerpts (#27850)

Release Notes:

- N/A

---------

Co-authored-by: Nathan Sobo <nathan@zed.dev>
Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

crates/editor/src/movement.rs

@@ -1089,14 +1089,8 @@ mod tests {
                 multibuffer.push_excerpts(
                     buffer.clone(),
                     [
-                        ExcerptRange {
-                            context: Point::new(0, 0)..Point::new(1, 4),
-                            primary: None,
-                        },
-                        ExcerptRange {
-                            context: Point::new(2, 0)..Point::new(3, 2),
-                            primary: None,
-                        },
+                        ExcerptRange::new(Point::new(0, 0)..Point::new(1, 4)),
+                        ExcerptRange::new(Point::new(2, 0)..Point::new(3, 2)),
                     ],
                     cx,
                 );