use only brands and solid icons from fontawesome and update assets

assets/fontawesomefree/js-packages/@fortawesome/fontawesome-free/scss/_icons.scss

@@ -5,5 +5,5 @@
 readers do not read off random characters that represent icons */
 
 @each $name, $icon in $fa-icons {
-  .#{$fa-css-prefix}-#{$name}::before { content: fa-content($icon); }
+  .#{$fa-css-prefix}-#{$name}::before { content: unquote("\"#{ $icon }\""); }
 }