vim: Update change surrounds to match vim's behavior (#38721)

These changes refactor the whitespace handling logic for Vim's change
surrounds command (`cs`), making its behavior closely match
[tpope/vim-surround](https://github.com/tpope/vim-surround), following
[this
discussion](https://github.com/zed-industries/zed/issues/38169#issuecomment-3304129461).

Zed's current implementation has two main differences when compared to
[tpope/vim-surround](https://github.com/tpope/vim-surround):

- It only considers whether a single space should be added or removed,
instead of all the space that is between the surrounding character and
the content
- It only takes into consideration the new surrounding characters in
order to determine whether to add or remove that space

A review of
[tpope/vim-surround](https://github.com/tpope/vim-surround)'s behavior
reveals these rules for whitespace:

* Quote to Quote
    * Whitespace is never changed
* Quote to Bracket
    * If opening bracket, add one space
    * If closing bracket, do not add space
* Bracket to Bracket
    * If opening to opening, keep only one space
    * If opening to closing, remove all space
    * If closing to opening, add one space
    * If closing to closing, do not change space
* Bracket to Quote
    * If opening, remove all space
    * If closing, preserve all space

Below is a table with examples for each scenario. A new test has also
been added to specifically check the scenarios outlined above,
`vim::surrounds::test::test_change_surrounds_vim`.

| Type              | Before      | Command | After         |
|-------------------|-------------|---------|---------------|
| Quote → Quote     | `'   a   '` | `cs'"`  | `"   a   "`   |
| Quote → Quote     | `"   a   "` | `cs"'`  | `'   a   '`   |
| Quote → Bracket   | `'   a   '` | `cs'{`  | `{    a    }` |
| Quote → Bracket   | `'   a   '` | `cs'}`  | `{   a   }`   |
| Bracket → Bracket | `[   a   ]` | `cs[{`  | `{ a }`       |
| Bracket → Bracket | `[   a   ]` | `cs[}`  | `{a}`         |
| Bracket → Bracket | `[   a   ]` | `cs]{`  | `{    a    }` |
| Bracket → Bracket | `[   a   ]` | `cs]}`  | `{   a   }`   |
| Bracket → Quote   | `[   a   ]` | `cs['`  | `'a'`         |
| Bracket → Quote   | `[   a   ]` | `cs]'`  | `'   a   '`   |

These changes diverge from
[tpope/vim-surround](https://github.com/tpope/vim-surround) when
handling newlines. For example, with the following snippet:

```rust
fn test_surround() {
    if 2 > 1 {
        println!("place cursor here");
    }
};
```

Placing the cursor inside the string and running any combination of
‎`cs{[`, ‎`cs{]`, ‎`cs}[`, or ‎`cs}]` would previously remove newline
characters. With these changes, using commands like ‎`cs}]` will now
preserve newlines.

Related to #38169
Closes #39334

Release Notes:

- Improved Vim’s change surround command to closely match
[tpope/vim-surround](https://github.com/tpope/vim-surround) behavior.

---------

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

crates/vim/src/vim.rs

@@ -678,6 +678,7 @@ impl Vim {
                     vim.push_operator(
                         Operator::ChangeSurrounds {
                             target: action.target,
+                            opening: false,
                         },
                         window,
                         cx,
@@ -945,6 +946,7 @@ impl Vim {
                 self.update_editor(cx, |_, editor, cx| {
                     editor.hide_mouse_cursor(HideMouseCursorOrigin::MovementAction, cx)
                 });
+
                 return;
             }
         } else if window.has_pending_keystrokes() || keystroke_event.keystroke.is_ime_in_progress()
@@ -1780,10 +1782,10 @@ impl Vim {
                 }
                 _ => self.clear_operator(window, cx),
             },
-            Some(Operator::ChangeSurrounds { target }) => match self.mode {
+            Some(Operator::ChangeSurrounds { target, opening }) => match self.mode {
                 Mode::Normal => {
                     if let Some(target) = target {
-                        self.change_surrounds(text, target, window, cx);
+                        self.change_surrounds(text, target, opening, window, cx);
                         self.clear_operator(window, cx);
                     }
                 }