Use xcursor whose scale matches to output's scale

[Aki-7]

In wlroots, for non-client-defined cursor, use appropriate xcursor theme whose scale factor matches to output's scale.

We should do as wlroots does.

See bellow for reference.

• https://gitlab.freedesktop.org/wlroots/wlroots/-/blob/0.15.0/types/wlr_xcursor_manager.c#L69-85
• https://gitlab.freedesktop.org/wlroots/wlroots/-/blob/0.15.0/types/wlr_cursor.c#L340-353