(Opt-in) Fix navbar styles

[isaaclyman]

Commit 39df6c3 introduced issues in sass/navbar.scss (https://github.com/HealthCatalyst/Fabric.Cashmere/blob/39df6c305bd2165761fddadb127b36a9f7aeb15c/projects/cashmere/src/lib/sass/navbar.scss).

• The navbar-brand, navbar-app, navbar-item, and navbar-link mixins do not begin with the hc- prefix.
• The navbar-brand mixin makes assumptions about the consumer's HTML structure; namely, that any siblings of the same type will have the class navbar-brand, that there will be a child element of class brand, and that state will be tracked via a no-switcher class. CSS properties are also not alphabetized.
• The navbar-app mixin makes assumptions as well, using element selectors where it should use unique classes with their own mixins. It also refers to a logo-condense class that doesn't have its own mixin.
• The navbar-link and navbar-item mixins have their CSS properties out of order.