Elements pool and drag drop (#2196)

* Implemented drag-and-drop composition

* Added composition policy for tables

* Reimplemented elements pool in Vue

* No need to resolve all objects on the navigated path

* Only show elements pool in edit mode

* Remove old elements pool

* Updated legacy code to use composition policy API

* Keep object in sync when mutated

platform/commonUI/edit/res/templates/elements.html

@@ -1,49 +0,0 @@
-<!--
- Open MCT, Copyright (c) 2014-2018, United States Government
- as represented by the Administrator of the National Aeronautics and Space
- Administration. All rights reserved.
-
- Open MCT is licensed under the Apache License, Version 2.0 (the
- "License"); you may not use this file except in compliance with the License.
- You may obtain a copy of the License at
- http://www.apache.org/licenses/LICENSE-2.0.
-
- Unless required by applicable law or agreed to in writing, software
- distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
- WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
- License for the specific language governing permissions and limitations
- under the License.
-
- Open MCT includes source code licensed under additional open source
- licenses. See the Open Source Licenses file (LICENSES.md) included with
- this source code distribution or the Licensing information page available
- at runtime from the About dialog for additional information.
--->
-<div ng-controller="ElementsController" class="flex-elem l-flex-col holder grows">
-    <mct-include key="'input-filter'"
-                 class="flex-elem holder"
-                 ng-model="filterBy">
-    </mct-include>
-    <div class="flex-elem grows vscroll scroll-pad">
-        <ul class="tree" id="inspector-elements-tree"
-            ng-if="composition.length > 0">
-            <li ng-repeat="containedObject in composition | filter:searchElements">
-                <span class="tree-item">
-                    <span class="grippy-sm"
-                          ng-if="composition.length > 1"
-                          data-id="{{ containedObject.id }}"
-                          mct-drag-down="dragDown($event)"
-                          mct-drag="drag($event)"
-                          mct-drag-up="dragUp($event)">
-                    </span>
-                    <mct-representation
-                            class="rep-object-label"
-                            key="'label'"
-                            mct-object="containedObject">
-                    </mct-representation>
-                </span>
-            </li>
-        </ul>
-        <div ng-if="composition.length === 0">No contained elements</div>    
-    </div>
-</div>