editor: Un-pub ScrollManager (#55767)

Make this only pub(crate) in preparation for
https://github.com/zed-industries/zed/pull/44827

Release Notes:

- N/A

crates/agent_ui/src/entry_view_state.rs

@@ -449,7 +449,7 @@ fn create_editor_diff(
         editor.set_show_vertical_scrollbar(false, cx);
         editor.set_minimap_visibility(MinimapVisibility::Disabled, window, cx);
         editor.set_soft_wrap_mode(SoftWrap::None, cx);
-        editor.scroll_manager.set_forbid_vertical_scroll(true);
+        editor.set_forbid_vertical_scroll(true);
         editor.set_show_indent_guides(false, cx);
         editor.set_read_only(true);
         editor.set_delegate_open_excerpts(true);

crates/agent_ui/src/inline_assistant.rs

@@ -1425,7 +1425,7 @@ impl InlineAssistant {
                     editor.set_show_gutter(false, cx);
                     editor.set_offset_content(false, cx);
                     editor.disable_mouse_wheel_zoom();
-                    editor.scroll_manager.set_forbid_vertical_scroll(true);
+                    editor.set_forbid_vertical_scroll(true);
                     editor.set_read_only(true);
                     editor.set_show_edit_predictions(Some(false), window, cx);
                     editor.highlight_rows::<DeletedLines>(

crates/editor/src/editor.rs

@@ -1157,7 +1157,12 @@ pub struct Editor {
     pub display_map: Entity<DisplayMap>,
     placeholder_display_map: Option<Entity<DisplayMap>>,
     pub selections: SelectionsCollection,
-    pub scroll_manager: ScrollManager,
+    /// Manages the scroll position for the given editor.
+    ///
+    /// Whenever you want to modify the scroll position of the editor, you should
+    /// usually use the existing available APIs as opposed to directly interacting
+    /// with the scroll manager.
+    pub(crate) scroll_manager: ScrollManager,
     /// When inline assist editors are linked, they all render cursors because
     /// typing enters text into each of them, even the ones that aren't focused.
     pub(crate) show_cursor_when_unfocused: bool,

crates/editor/src/scroll.rs

@@ -623,6 +623,14 @@ impl Editor {
         self.scroll_manager.has_autoscroll_request()
     }
 
+    pub fn set_forbid_vertical_scroll(&mut self, forbid: bool) {
+        self.scroll_manager.set_forbid_vertical_scroll(forbid);
+    }
+
+    pub fn scroll_top_display_point(&self, snapshot: &DisplaySnapshot, cx: &App) -> DisplayPoint {
+        self.scroll_manager.scroll_top_display_point(snapshot, cx)
+    }
+
     pub fn vertical_scroll_margin(&self) -> usize {
         self.scroll_manager.vertical_scroll_margin as usize
     }

crates/vim/src/normal/scroll.rs

@@ -109,9 +109,7 @@ impl Vim {
         self.update_editor(cx, |vim, editor, cx| {
             let should_move_cursor = editor.newest_selection_on_screen(cx).is_eq();
             let display_snapshot = editor.display_map.update(cx, |map, cx| map.snapshot(cx));
-            let old_top = editor
-                .scroll_manager
-                .scroll_top_display_point(&display_snapshot, cx);
+            let old_top = editor.scroll_top_display_point(&display_snapshot, cx);
 
             if editor.scroll_hover(amount, window, cx) {
                 return;
@@ -143,9 +141,7 @@ impl Vim {
             };
 
             let display_snapshot = editor.display_map.update(cx, |map, cx| map.snapshot(cx));
-            let top = editor
-                .scroll_manager
-                .scroll_top_display_point(&display_snapshot, cx);
+            let top = editor.scroll_top_display_point(&display_snapshot, cx);
             let vertical_scroll_margin = EditorSettings::get_global(cx).vertical_scroll_margin;
 
             let mut move_cursor = |map: &editor::display_map::DisplaySnapshot,