Differential review to add new media types to if_media.h

[Eric Joyner]

https://reviews.freebsd.org/D10425

I didn't add any reviewers yet because we have yet to test this, and I
didn't have a good idea of who would be interested in these. Suggestions on
the string to give the active optical/copper cable types would be welcome;
I gave them the acronyms I saw in SFF-8024, but I also considered spelling
them out, like e.g. "25GBase-Active-Optical".

- Eric