Introduce WSU wishlist functions for wordPress Core

Mostly dealing around things that we want to happen at the multi network level.

Initial development was in the WSUWP Environment repository, history is here:

https://github.com/washingtonstateuniversity/WSUWP-Environment/commits/68ff7804c2859c0fca5fed9e6baf4e8ff1fd5dd8/www/wp.wsu.edu/content/mu-plugins/wsu-core-functions.php
Introduce WSU Network Admin mu-plugin

Customizes various aspects of network administration.

Development was originally done as part of wSUWP Environment, history is here:

https://github.com/washingtonstateuniversity/WSUWP-Environment/commits/68ff7804c2859c0fca5fed9e6baf4e8ff1fd5dd8/www/wp.wsu.edu/content/mu-plugins/wsu-network-admin.php
Add a customized WSUWP Admin Header

Switches things up to start working with multi network

This was developed originally as part of the WSUWP Environment repo, history is here:

https://github.com/washingtonstateuniversity/WSUWP-Environment/commits/68ff7804c2859c0fca5fed9e6baf4e8ff1fd5dd8/www/wp.wsu.edu/content/mu-plugins/wsu-admin-header.php
Remove many of the default dashboard widgets at the network and individual site level