Hyrax v4/v5 - CSS & Bootstrap Updates

[CGillen]

Descriptive summary

Bootstrap upgraded from v3 to v4 and with that pretty much ALL of the css class naming scheme.
For example .visible-sm.visible-xs would become .d-none-md.

Expected behavior

Site style, color, theme, and custom elements are restored

Related work

child issue to: #3210

Accessibility Concerns

Biggest one: Bootstrap custom elements (dropdowns, modals, etc) are restored, function the same, and are still accessible
Colors need to match
Tab order stays same
Elements haven't disappeared