[bug#49258] [PATCH] Add wondershaper package and service

[Aljosha Papsch]

Hello Guix! 

These patches add a package and service for Wonder Shaper, a nice 
little tool configuring traffic control. The defaults should suffice 
for desktop usage, with the exception of download-speed and upload-speed, 
which must be chosen according to your actual speeds. 

I forked the upstream repository and the package uses the fork. It's not 
meant as a long lived fork. Currently the tool doesn't provide a way 
to specify the config file, users are expected to edit the script. A patch 
is pending upstream (https://github.com/magnific0/wondershaper/pull/68) 
to add a CLI option but in the meantime wondershaper-service would have 
to jump through some hoops to specify the options. 

While at it, I also added two other options for the maximum rate and burst 
rate for the lowest priority traffic class. My goal is to make data 
exfiltration harder in a server environment and a custom rate seems just 
right for that. I plan to send these options upstream as well. If you don't
like exposing non-upstream options, an alternative could be to instead  
expose a list of pairs for arbitrary additional options which get pasted 
into the configuration file. 

Best regards 
Aljosha