vim: Add motion support for toggle comments (#14919)

### Summary

This PR adds support for count and object motions to the toggle comments
action in Vim mode. The relevant issue is
[#14337](https://github.com/zed-industries/zed/issues/14337).

For example, `2 g c j` will toggle comments three lines downward. `g c g
g` will toggle comments from the current cursor position up to the start
of the file.

Notably missing from this PR are `g c b` (toggle comments for the
current block) as well as `g c p` (toggle comments for the current
paragraph). These seem to be non-standard.

The new module `normal/toggle_comments.rs` has been copied almost
verbatim from `normal/indent.rs`. Maybe that ought to be abstracted over
but I feel I lack the overview.

Release Notes:

- vim: Added support for count and object motion to the toggle comments
action ([#14337](https://github.com/zed-industries/zed/issues/14337)).

crates/vim/src/normal/toggle_comments.rs

@@ -0,0 +1,57 @@
+use crate::{motion::Motion, object::Object, Vim};
+use collections::HashMap;
+use editor::{display_map::ToDisplayPoint, Bias};
+use gpui::WindowContext;
+use language::SelectionGoal;
+
+pub fn toggle_comments_motion(
+    vim: &mut Vim,
+    motion: Motion,
+    times: Option<usize>,
+    cx: &mut WindowContext,
+) {
+    vim.stop_recording();
+    vim.update_active_editor(cx, |_, editor, cx| {
+        let text_layout_details = editor.text_layout_details(cx);
+        editor.transact(cx, |editor, cx| {
+            let mut selection_starts: HashMap<_, _> = Default::default();
+            editor.change_selections(None, cx, |s| {
+                s.move_with(|map, selection| {
+                    let anchor = map.display_point_to_anchor(selection.head(), Bias::Right);
+                    selection_starts.insert(selection.id, anchor);
+                    motion.expand_selection(map, selection, times, false, &text_layout_details);
+                });
+            });
+            editor.toggle_comments(&Default::default(), cx);
+            editor.change_selections(None, cx, |s| {
+                s.move_with(|map, selection| {
+                    let anchor = selection_starts.remove(&selection.id).unwrap();
+                    selection.collapse_to(anchor.to_display_point(map), SelectionGoal::None);
+                });
+            });
+        });
+    });
+}
+
+pub fn toggle_comments_object(vim: &mut Vim, object: Object, around: bool, cx: &mut WindowContext) {
+    vim.stop_recording();
+    vim.update_active_editor(cx, |_, editor, cx| {
+        editor.transact(cx, |editor, cx| {
+            let mut original_positions: HashMap<_, _> = Default::default();
+            editor.change_selections(None, cx, |s| {
+                s.move_with(|map, selection| {
+                    let anchor = map.display_point_to_anchor(selection.head(), Bias::Right);
+                    original_positions.insert(selection.id, anchor);
+                    object.expand_selection(map, selection, around);
+                });
+            });
+            editor.toggle_comments(&Default::default(), cx);
+            editor.change_selections(None, cx, |s| {
+                s.move_with(|map, selection| {
+                    let anchor = original_positions.remove(&selection.id).unwrap();
+                    selection.collapse_to(anchor.to_display_point(map), SelectionGoal::None);
+                });
+            });
+        });
+    });
+}