Dark Theme (#1017)

* Stylesheets

* Theme Configuration

* Options Area

* swal2 style

* Icon styling

* Fix theme not saving

* Update English

* Update messages.json

* dropdown and login logo

* btn-link and totp fix

* Organisation Styling

* Update webauthn-fallback.ts

* Fix contrast issues

* Add Paypal Container and Loading svg file

* Password Generator contrast fix

* Dark Mode Fix buttons and foreground

* Fix button hover

* Fix Styles after rebase

* Add hover on nav dropdown-item

* Disable Theme Preview

* Options Fix for Default Theme Changes

* Updated Colour Scheme

* Toast fix

* Button and Text Styling

* Options Update and Messages Fix

* Added Search Icon and Fixed Callout styling

* Add theme styling to Stripe

* Refactor logic for setting color

* Reorder logic to avoid race condition

* PayPal Loading and Misc Fix

* text-state bug fix

* Badge Colour Fix

* Remove PayPal Tagline

The colour cannot be styled so it's not visible on a dark theme

* Adding the Styling from #1131

* Update to New Design

* Form and Nav restyle

* Modal Opacity and Callout

* Nav Colours

* Missing Borders

* Light theme fix

* Improved border for listgroup

* Change Org Nav Colour

* Save theme to localStorage for persistence

* Undo change to Wired image

* !Important removal and tweaks

* Fix regression with navbar

* Light theme by default

* Refactor to use getEffectiveTheme

* Refactor theme constants to use enum

* Set theme in index.html before app loads

* Use scss selector to set logo image

* Export Sass to TS

* Update jslib

Co-authored-by: Thomas Rittson <trittson@bitwarden.com>

src/images/loading-white.svg

@@ -0,0 +1,6 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="100%" height="100%" viewBox="0 0 100% 100%">
+  <text fill="%23FBFBFB" x="50%" y="50%" font-family="\'Open Sans\', \'Helvetica Neue\', Helvetica, Arial, sans-serif"
+        font-size="18" text-anchor="middle">
+    Loading...
+  </text> 
+</svg>