### Godot version

4.1

### System information

Windows

### Issue description

Being able to have multiple cursors similarly to vscode is a great feature, however it's only possible to add carets, not remove them. By left clicking you can remove all extra cursors but you cannot remove a specific one so after selecting multiple lines a single missclick, you have to reselect them all again. Looking at the original pr there was a remove_caret function added so it would make sense to be able to remove carets when clicking again, like in vscode.

![image](https://github.com/godotengine/godot/assets/19669673/3867c00e-9faa-4429-9c6d-f2d6d3883044)


### Steps to reproduce

- Alt click to add multiple carets
- Alt click on the same position again
- Nothing happens

### Minimal reproduction project

N/A
if (!selecting_enabled) {
		return;
	}
	if (!has_selection(p_caret) || get_selection_mode() == SelectionMode::SELECTION_MODE_NONE) {
		carets.write[p_caret].selection.active = true;
		set_selection_mode(SelectionMode::SELECTION_MODE_SHIFT, get_caret_line(p_caret), get_caret_column(p_caret), p_caret);
		return;
	}
	set_selection_mode(SelectionMode::SELECTION_MODE_SHIFT, get_selection_line(p_caret), get_selection_column(p_caret), p_caret);
}
void TextEdit::_post_shift_selection(int p_caret) {