fix(icons): scope white svgs to Icon components

css/_base.scss

     }
 }
 
-svg {
+.jitsi-icon svg {
     fill: white;
 }
 

react/features/base/icons/components/Icon.js

     /**
      * Class name for the web platform, if any.
      */
-    className?: string,
+    className: string,
 
     /**
      * Color of the icon (if not provided by the style object).
 
     return (
         <Container
-            className = { className }
+            className = { `jitsi-icon ${className}` }
             style = { restStyle }>
             <IconComponent
                 fill = { calculatedColor }
     );
 }
 
+Icon.defaultProps = {
+    className: ''
+};