Add mouse_warp to mark option

This allows to better support certain pop-ups which require focus or they close (like certain password managers).
The popup can be marked and only that window will get mouse_warped.

For example:
```
for_window [title="Enpass Assistant"] {
    move position mouse
    inhibit_idle visible
    urgent enable
    mark --add mouse_me
}

mouse_warping mark mouse_me
```

include/sway/config.h

@@ -472,6 +472,7 @@ enum mouse_warping_mode {
 	WARP_NO,
 	WARP_OUTPUT,
 	WARP_CONTAINER,
+	WARP_MARK,
 };
 
 enum alignment {
@@ -537,6 +538,7 @@ struct sway_config {
 	// Flags
 	enum focus_follows_mouse_mode focus_follows_mouse;
 	enum mouse_warping_mode mouse_warping;
+	char *mouse_warping_mark_name;
 	enum focus_wrapping_mode focus_wrapping;
 	bool active;
 	bool failed;