IOTS-322: Infroming users when device types are not installed

Currently policy platfom selection page is empty if no device types are installed. This will add an meaningful message to user if no device types are added.

This commit resolves IOTS-322

components/device-mgt/org.wso2.carbon.device.mgt.ui/src/main/resources/jaggeryapps/devicemgt/app/units/cdmf.unit.policy.create/create.hbs

@@ -283,9 +283,14 @@
                                 <div id="policy-platform-main-error-msg" class="alert alert-danger hidden" role="alert">
                                     <i class="icon fw fw-error"></i><span></span>
                                 </div>
+                                {{#unless types}}
+                                <h3><i class="icon fw fw-warning"></i> No compatible device types have been installed.
+                                    Install device types to add policies.</h3>
+                                {{/unless}}
                                 <div class="row wr-tile-buttons-list">
                                     <div class="wr-input-control">
                                         <ul class="tile-buttons row">
+                                            {{#if types}}
                                                 {{#each types}}
                                                     <li class="col-xs-12 col-sm-12 col-md-4 col-lg-4"
                                                         style="margin-top: 5px; margin-bottom: 5px;">
@@ -300,6 +305,7 @@
                                                         </a>
                                                     </li>
                                                 {{/each}}
+                                            {{/if}}
                                         </ul>
                                     </div>
                                 </div>