Add a new DOI icon (#7357)

* Add a new DOI icon

Add an extra icon font for the DOI icon, an icon font was needed in order to colour and size the new DOI icon in the same way as all the FontAwesome icons

* Update name of the font file and remove unused `css` code

* Update the internal name of the font and moved the file up one directory

web-ui/src/main/resources/catalog/style/gn_icons.less

@@ -3,6 +3,11 @@
 @import "../lib/style/font-awesome/less/_shims";
 @import "../lib/style/bootstrap/less/variables.less";
 
+@font-face {
+  font-family: "geonetwork";
+  src: url("../catalog/style/gn.ttf") format("truetype");
+}
+
 /* used to display icons with resource types - iso19139 hierarchylevel */
 .gn-icon-dataset:before,
 .gn-icon-datasets:before {
@@ -245,8 +250,17 @@
   content: @fa-var-file-zipper;
 }
 
+.gn-icon-doi {
+  display: inline-block;
+  font: normal normal normal 1em/1 "geonetwork";
+  color: inherit;
+  flex-shrink: 0;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+}
+
 .gn-icon-doi:before {
-  content: @fa-var-info-circle;
+  content: "\ea01";
 }
 
 .gn-icon-parent:before {