Allow login buttons in place of eyebrow links or search

[bryanjonker-illinois]

https://app-illinois.github.io/Design-Resources/Login-Button.html

Allow nice handling of <span>jonker@illinois.edu</span> <a href="/logout">Logout</a> in the following slots:

• slot="search"
• slot="links"

Span is optional, button can be a link or button

[bryanjonker-illinois]

Need to increase the size of the buttons to meet AAA