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

plugins/poll/assets/javascripts/discourse/templates/modal/poll-ui-builder.hbs

@@ -73,5 +73,5 @@
 {{/d-modal-body}}
 
 <div class="modal-footer">
-  {{d-button action="insertPoll" icon="bar-chart-o" class='btn-primary' label='poll.ui_builder.insert' disabled=disableInsert}}
+  {{d-button action="insertPoll" icon="chart-bar" class='btn-primary' label='poll.ui_builder.insert' disabled=disableInsert}}
 </div>