Icons: Add icon for wpa_supplicant

This was the last system daemon/server to not have an icon, so I thought I'd give a go at this!
This icon will still need to be added to Haiku's wpa_supplicant repository however.

Change-Id: Icd4e60ec759daaece30669aa8125fce953bbbf95
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2698
Reviewed-by: waddlesplash <waddlesplash@gmail.com>