feat: disable delete button for contributors that are not signed on

#2251

Author: jo-elimu

pom-dependency-tree.txt

@@ -1,4 +1,4 @@
-ai.elimu:webapp:war:2.6.124-SNAPSHOT
+ai.elimu:webapp:war:2.6.125-SNAPSHOT
 +- ai.elimu:model:jar:model-2.0.120:compile
 |  \- com.google.code.gson:gson:jar:2.13.1:compile
 |     \- com.google.errorprone:error_prone_annotations:jar:2.38.0:compile

src/main/webapp/WEB-INF/jsp/content/storybook/edit.jsp

@@ -110,7 +110,7 @@
             <button id="submitButton" class="btn-large waves-effect waves-light" type="submit" <c:if test="${empty contributor}">disabled</c:if>>
                 Edit <i class="material-icons right">send</i>
             </button>
-            <a href="<spring:url value='/content/storybook/delete/${storyBook.id}' />" class="waves-effect waves-red red-text btn-flat right">Delete</a>
+            <a href="<spring:url value='/content/storybook/delete/${storyBook.id}' />" class="waves-effect waves-red red-text btn-flat <c:if test='${empty contributor}'>disabled</c:if> right">Delete</a>
         </form:form>
     </div>