FEATURE: Update Font Awesome to v5.4.1 and SVGs (#6557)

* First take on subsetting svg icons

* FontAwesome 5 svg subset WIP

* Include icons from plugins/badges into svg sprite subset

* add svg icon support to themes

* Add spec for SvgSprite

* Misc. SVG icon fixes

* Use FA5 svgs in local-dates plugin

* CSS adjustments, fix SVG icons in group flair

* Use SVG icons in poll plugin

* Add SVG icons to /wizard

test/javascripts/acceptance/group-index-test.js.es6

@@ -6,7 +6,7 @@ QUnit.test("Viewing Members as anon user", async assert => {
   await visit("/groups/discourse");
 
   assert.ok(
-    count(".avatar-flair .fa-adjust") === 1,
+    count(".avatar-flair .d-icon-adjust") === 1,
     "it displays the group's avatar flair"
   );
   assert.ok(count(".group-members tr") > 0, "it lists group members");