Remove isVisibleToAll from GroupDescription

The notion of who can view a group is a security detail that
belongs delegated to the group backend and should not be part
of the public GroupDescription.Basic interface.

Drop it and move the code into the internal group backend only.

Change-Id: Ia967e957147860fe98d1a4d74b005d63f48e4343

gerrit-common/src/main/java/com/google/gerrit/common/data/GroupDescription.java

@@ -32,9 +32,6 @@ public class GroupDescription {
     /** @return the non-null name of the group. */
     String getName();
 
-    /** @return whether the group is visible to all accounts. */
-    boolean isVisibleToAll();
-
     /**
      * @return optional email address to send to the group's members. If
      *         provided, Gerrit will use this email address to send

gerrit-common/src/main/java/com/google/gerrit/common/data/GroupDescriptions.java

@@ -44,11 +44,6 @@ public class GroupDescriptions {
         return group.getName();
       }
 
-      @Override
-      public boolean isVisibleToAll() {
-        return group.isVisibleToAll();
-      }
-
       @Override
       public AccountGroup getAccountGroup() {
         return group;