Core: New workflow for RichGroup

 - added method getAllRichGroupsWithAttributesByNames(PerunSession sess, Vo vo, List<String> attrNames) into GroupsManager
 - added method getRichSubGroupsWithAttributesByNames(PerunSession sess, Group parentGroup, List<String> attrNames) into GroupsManager
 - added method getRichGroupByIdWithAttributesByNames(PerunSession sess, int groupId, List<String> attrNames) into GroupsManager
 - added method convertGroupsToRichGroupsWithAttributes(PerunSession sess, List<Group> groups, List<String> attrNames) into GroupsManagerBl
 - added method convertGroupsToRichGroupsWithAttributes(PerunSession sess, List<Group> groups) into GroupsManagerBl
 - added method convertGroupToRichGroupWithAttributesByName(PerunSession sess, Group group, List<String> attrNames) into GroupsManagerBl
 - added method convertGroupToRichGroupWithAttributes(PerunSession sess, Group group) into GroupsManagerBl