[Icons] Remove unused imports from MCTIcons

Author: VWoeltjen

util/src/main/java/gov/nasa/arc/mct/util/MCTIcons.java

@@ -39,8 +39,6 @@
 import java.util.Map;
 
 import javax.swing.ImageIcon;
-import javax.swing.JFrame;
-import javax.swing.JLabel;
 
 /**
  * MCT icons for errors, warnings and component object.