vim: Surround in visual mode (#13347)

Adds support for surrounding text in visual/visual-line/visual-block
mode by re-using the `AddSurrounds` operator. There is no default
binding though so the user must follow the instructions to enable it.

Note that the behaviour varies slightly for the visual-line and
visual-block modes. In visual-line mode the surrounds are placed on
separate lines (the vim-surround extension also indents the contents but
I opted not to as that behaviour is less important with the use of code
formatters). In visual-block mode each of the selected regions is
surrounded and the cursor returns to the beginning of the selection
after the action is complete.

Release Notes:

- Added action to surround text in visual mode (no default binding).

Fixes #13122

crates/vim/src/state.rs

@@ -287,7 +287,10 @@ impl EditorState {
                 .unwrap_or_else(|| "none"),
         );
 
-        if self.mode == Mode::Replace {
+        if self.mode == Mode::Replace
+            || (matches!(active_operator, Some(Operator::AddSurrounds { .. }))
+                && self.mode.is_visual())
+        {
             context.add("VimWaiting");
         }
         context