[feat] lighter icons for darwin

icon/blocked_darwin.go

icon/off_darwin.go

icon/on_darwin.go

icon/png/black/vpn_blocked.png

icon/png/black/vpn_off.png

icon/png/black/vpn_on.png

icon/png/black/vpn_wait_0.png

icon/png/black/vpn_wait_1.png

icon/png/black/vpn_wait_2.png

icon/png/black/vpn_wait_3.png

icon/wait_0_darwin.go

icon/wait_1_darwin.go

icon/wait_2_darwin.go

icon/wait_3_darwin.go