Add a Sign-In Popup

[spelkey-ucd]

As detailed in this RT, the librarians would like to add a popup to Primo with the following functional requirements when visiting any Primo page:

1. Code runs that detects if user's IP is within the range allocated to UC Davis
2. If not, a popup is triggered that informs user they will have limited access to resources unless on VPN
3. A cookie is set so the previous two steps are not performed everytime a person visits a page

To better fit in with our overall web-component-based architecture, the following things need to happen:

1. Make a controller in the theme components repo that does the IP verification process. Issue 51.
2. Our Webpack JS build process should be used instead of the default Browserify process used by Ex Libris.
   When running gulp run --view ${VIEW} --proxy ${PROXY} --ve --browserify, replace the --browserify flag with a new custom flag (--cork-app-build) that will tell gulp to run our own build process instead.
3. Make a Lit element in this repository that loads the IP verification controller, and displays popup/sets cookie.

Finally, the design/language of the popup needs to be vetted by Communications/Online Strategy (Kristin and Kimmy).