Use consistent ordering for popup menus (#27765)

Before this change, the editor completion menu and gutter menus reversed their order so that the initial selection is near the user's focus.  This change instead displays these menus in a consistent top-to-bottom order because the following benefits outweigh that benefit:

* Matches behavior of some other editors (Neovim and VSCode).
* Looks better for lexicographic lists.
* Keeps the meaning of keyboard interaction consistent, if the user is anticipating the order of the menu's contents.

Could consider making this configurable in the future if desired.

Closes #25066.

Release Notes:

- N/A

crates/editor/src/code_context_menus.rs

@@ -126,16 +126,15 @@ impl CodeContextMenu {
         &self,
         style: &EditorStyle,
         max_height_in_lines: u32,
-        y_flipped: bool,
         window: &mut Window,
         cx: &mut Context<Editor>,
     ) -> AnyElement {
         match self {
             CodeContextMenu::Completions(menu) => {
-                menu.render(style, max_height_in_lines, y_flipped, window, cx)
+                menu.render(style, max_height_in_lines, window, cx)
             }
             CodeContextMenu::CodeActions(menu) => {
-                menu.render(style, max_height_in_lines, y_flipped, window, cx)
+                menu.render(style, max_height_in_lines, window, cx)
             }
         }
     }
@@ -439,7 +438,6 @@ impl CompletionsMenu {
         &self,
         style: &EditorStyle,
         max_height_in_lines: u32,
-        y_flipped: bool,
         window: &mut Window,
         cx: &mut Context<Editor>,
     ) -> AnyElement {
@@ -589,7 +587,6 @@ impl CompletionsMenu {
         .occlude()
         .max_h(max_height_in_lines as f32 * window.line_height())
         .track_scroll(self.scroll_handle.clone())
-        .y_flipped(y_flipped)
         .with_width_from_item(widest_completion_ix)
         .with_sizing_behavior(ListSizingBehavior::Infer);
 
@@ -978,7 +975,6 @@ impl CodeActionsMenu {
         &self,
         _style: &EditorStyle,
         max_height_in_lines: u32,
-        y_flipped: bool,
         window: &mut Window,
         cx: &mut Context<Editor>,
     ) -> AnyElement {
@@ -1068,7 +1064,6 @@ impl CodeActionsMenu {
         .occlude()
         .max_h(max_height_in_lines as f32 * window.line_height())
         .track_scroll(self.scroll_handle.clone())
-        .y_flipped(y_flipped)
         .with_width_from_item(
             self.actions
                 .iter()