use only brands and solid icons from fontawesome and update assets

assets/fontawesomefree/less/_core.less

@@ -1,24 +1,24 @@
 // base icon class definition
 // -------------------------
 
-@{fa-css-prefix} {
+.@{fa-css-prefix} {
   font-family: ~'var(--@{fa-css-prefix}-style-family, @{fa-style-family})';
   font-weight: ~'var(--@{fa-css-prefix}-style, @{fa-style})';
 }
 
 .@{fa-css-prefix},
 .fas,
-.fa-solid,
+.@{fa-css-prefix}--solid,
 .far,
-.fa-regular,
+.@{fa-css-prefix}--regular,
 .fal,
-.fa-light,
+.@{fa-css-prefix}--light,
 .fat,
-.fa-thin,
+.@{fa-css-prefix}--thin,
 .fad,
-.fa-duotone,
+.@{fa-css-prefix}--duotone,
 .fab,
-.fa-brands {
+.@{fa-css-prefix}--brands {
   -moz-osx-font-smoothing: grayscale;
   -webkit-font-smoothing: antialiased;
   display: ~'var(--@{fa-css-prefix}-display, @{fa-display})';