New port: sysutils/solaar

Solaar is a device manager for Logitech's Unifying Receiver. It is
able to pair/unpair devices to the receiver, and for most devices read
battery status.

It comes in two flavors, command-line and GUI. Both are able to list
the devices paired to a Unifying Receiver, show detailed info for each
device, and also pair/unpair supported devices with the receiver.

WWW: https://pwr.github.io/Solaar/

Approved by: mat (mentor)
Differential Revision: https://reviews.freebsd.org/D10155