Timeline, added i18n labels in context menu

config/locales/js-en.yml

@@ -297,6 +297,8 @@ en:
       remove_child: "Remove child"
       add_new_relation: "Create new relation"
       update_description: "Set or update description of this relation"
+      add_follower: "Add follower"
+      add_predecessor: "Add predecessor"
       remove: "Remove relation"
       save: "Save relation"
       abort: "Abort"

frontend/app/components/wp-table/context-menu-helper/wp-context-menu-helper.service.ts

@@ -114,12 +114,12 @@ function WorkPackageContextMenuHelper(
     if (states.table.timelineVisible.getCurrentValue()) {
       allowedActions.push({
         icon: "timeline-relation-add-predecessor",
-        text: "add-predecessor",
+        text: I18n.t("js.relation_buttons.add_predecessor"),
         link: "addRelation"
       });
       allowedActions.push({
         icon: "timeline-relation-add-follower",
-        text: "add-follower",
+        text: I18n.t("js.relation_buttons.add_follower"),
         link: "addRelation"
       });
     }