Add GitHub icon to our font (matomo-org#18712)

* Add a github icon

* Fix UI test

Author: tsteur

LEGALNOTICE

@@ -283,7 +283,7 @@ THIRD-PARTY CONTENT
 	Link: https://design.google.com/icons/
 	License: Apache License Version 2.0
 
-	Name: IcoMoon - Free icons ("icon-funnel", "icon-lab", "icon-archive", "icon-rocket", "icon-embed", "icon-page-performance") in plugins/Morpheus/fonts
+	Name: IcoMoon - Free icons ("icon-funnel", "icon-lab", "icon-archive", "icon-rocket", "icon-embed", "icon-page-performance", "icon-github") in plugins/Morpheus/fonts
 	Link: https://icomoon.io/#icons-icomoon
 	License: GPL
 

plugins/Morpheus/fonts/matomo.svg

@@ -127,6 +127,9 @@
 .icon-fullscreen:before {
   content: "\e61c";
 }
+.icon-github:before {
+  content: "\eab0";
+}
 .icon-goal:before {
   content: "\e61d";
 }
@@ -399,4 +402,4 @@
 }
 .icon-new_releases:before {
   content: "\e902";
-}
+}

plugins/Morpheus/fonts/matomo.ttf

@@ -720,6 +720,7 @@
                         'finance',
                         'folder',
                         'folder-charts',
+                        'github',
                         'open-source',
                         'puzzle',
                         'server',