Add localization key for 'Cancel and clear query'

src/Umbraco.Core/EmbeddedResources/Lang/en.xml

@@ -1504,6 +1504,7 @@ To manage your website, simply open the Umbraco backoffice and start adding cont
     <key alias="queryStepTypes">That matches types: </key>
     <key alias="noValidStartNodeTitle">No matching content</key>
     <key alias="noValidStartNodeDesc">The configuration of this property does not match any content. Create the missing content or contact your administrator to adjust the Dynamic Root settings for this property.</key>
+    <key alias="cancelAndClearQuery">Cancel and clear query</key>
   </area>
   <area alias="mediaPicker">
     <key alias="deletedItem">Deleted item</key>

src/Umbraco.Core/EmbeddedResources/Lang/en_us.xml

@@ -1509,6 +1509,7 @@ To manage your website, simply open the Umbraco backoffice and start adding cont
     <key alias="queryStepTypes">That matches types: </key>
     <key alias="noValidStartNodeTitle">No matching content</key>
     <key alias="noValidStartNodeDesc">The configuration of this property does not match any content. Create the missing content or contact your administrator to adjust the Dynamic Root settings for this property.</key>
+    <key alias="cancelAndClearQuery">Cancel and clear query</key>
   </area>
   <area alias="mediaPicker">
     <key alias="deletedItem">Deleted item</key>

src/Umbraco.Web.UI.Client/src/views/prevalueeditors/treesource.html

@@ -155,7 +155,7 @@
         <ul class="unstyled list-icons mt3">
           <li>
             <umb-icon icon="icon-delete" class="icon red"></umb-icon>
-            <button type="button" class="btn-link" ng-click="clearDynamicStartNode()">Cancel and clear query</button>
+            <button type="button" class="btn-link" ng-click="clearDynamicStartNode()"><localize key="dynamicRoot_cancelAndClearQuery">Cancel and clear query</localize></button>
           </li>
         </ul>
       </div>