Adds id and testid for item overflow button (#26092)

Author: alecharp

core/src/main/resources/lib/layout/job-subpage.jelly

@@ -103,7 +103,7 @@ THE SOFTWARE.
                 </j:when>
               </j:choose>
 
-              <l:overflowButton>
+              <l:overflowButton id="more-item-actions">
                 <dd:custom>
                   <div class="app-build-overflow">
                     <j:set var="mode" value="side-panel" />

core/src/main/resources/lib/layout/overflowButton.jelly

@@ -44,13 +44,17 @@ THE SOFTWARE.
     <st:attribute name="id">
       Optional ID for the button
     </st:attribute>
+    <st:attribute name="testid">
+      Optional test id for the button. Will be rendered as `data-testid`. Defaults to id if provided or empty.
+    </st:attribute>
 
     Displays a button which when clicked displays a dropdown of the component's children
   </st:documentation>
 
   <button class="jenkins-button ${attrs.clazz}"
           tooltip="${attrs.containsKey('tooltip') ? attrs.tooltip : '%More actions'}"
           id="${attrs.id}"
+          data-testid="${attrs.containsKey('testId') ? attrs.testid  : attrs.containsKey('id') ? attrs.id : ''}"
           type="button" data-dropdown="true">
     <j:choose>
       <j:when test="${attrs.containsKey('icon')}">