[Create] Add filter to copyService

Add an optional parameter to method signature of
copyService, used to determine if a domain object should
or should not be cloned.

This will be used to support usages of copyService
where links should remain links;
https://github.com/nasa/openmctweb/pull/666/files#r52525612

platform/entanglement/src/services/CopyService.js

@@ -54,16 +54,33 @@ define(
             );
         };
 
+        /**
+         * A function used to check if a domain object should be cloned
+         * or not.
+         * @callback platform/entanglement.CopyService~filter
+         * @param {DomainObject} domainObject the object to be cloned
+         * @returns {boolean} true if the object should be cloned; false
+         *          if it should be linked
+         */
+
         /**
          * Creates a duplicate of the object tree starting at domainObject to
          * the new parent specified.
-         * @param domainObject
-         * @param parent
-         * @param progress
+         *
+         * Any domain objects which cannot be created will not be cloned;
+         * instead, these will appear as links. If a filtering function
+         * is provided, any objects which fail that check will also be
+         * linked instead of cloned
+         *
+         * @param {DomainObject} domainObject the object to duplicate
+         * @param {DomainObject} parent the destination for the clone
+         * @param {platform/entanglement.CopyService~filter} [filter]
+         *        an optional function used to filter out objects from
+         *        the cloning process
          * @returns a promise that will be completed with the clone of
          * domainObject when the duplication is successful.
          */
-        CopyService.prototype.perform = function (domainObject, parent) {
+        CopyService.prototype.perform = function (domainObject, parent, filter) {
             var $q = this.$q,
                 copyTask = new CopyTask(domainObject, parent, this.policyService, this.$q);
             if (this.validate(domainObject, parent)) {