vim: Maintain block cursor for navigating/non-modifying operators (#21502)

The cursor shape now only changes to underline for operators that modify
text (like: delete, change, yank) while maintaining block shape for
navigation operators (like: find, till).

This better matches Vim/Nvim's behavior where the cursor only changes
shape when an operator that will modify text is pending.

Release Notes:

- vim: Improved cursor shape behavior to better match Vim

crates/vim/src/vim.rs

@@ -626,10 +626,23 @@ impl Vim {
     pub fn cursor_shape(&self) -> CursorShape {
         match self.mode {
             Mode::Normal => {
-                if self.operator_stack.is_empty() {
-                    CursorShape::Block
+                if let Some(operator) = self.operator_stack.last() {
+                    match operator {
+                        // Navigation operators -> Block cursor
+                        Operator::FindForward { .. }
+                        | Operator::FindBackward { .. }
+                        | Operator::Mark
+                        | Operator::Jump { .. }
+                        | Operator::Register
+                        | Operator::RecordRegister
+                        | Operator::ReplayRegister => CursorShape::Block,
+
+                        // All other operators -> Underline cursor
+                        _ => CursorShape::Underline,
+                    }
                 } else {
-                    CursorShape::Underline
+                    // No operator active -> Block cursor
+                    CursorShape::Block
                 }
             }
             Mode::Replace => CursorShape::Underline,