[Fedora-packaging] Packaging fish config files

[Orion Poplawski]

Background - https://bugzilla.redhat.com/show_bug.cgi?id=1878306

conda can provide an /etc/fish/conf.d/conda.fish file for fish users. 
As usual, we do not want to add a dependency on fish for conda.  For now 
I think I'll just have conda own /etc/fish and /etc/fish/conf.d, but 
what do we want to do going forward?  Add it to filesystem?  Create a 
fish-filesystem package?

Surprisingly, I can't find any other packages that ship 
/etc/fish/conf.d/* files, so maybe this just isn't an issue worth taking 
on yet.

Thanks,
   Orion