Add a lock icon for admin actions.

* src/cuirass/templates.scm (build-details, evaluation-info-table): Add lock
icons for admin actions.

src/cuirass/templates.scm

@@ -302,10 +302,10 @@ system whose names start with " (code "guile-") ":" (br)
                   (aria-expanded "false"))
                "Action")
             (div (@ (class "dropdown-menu"))
-                 (a (@ (class "dropdown-item")
+                 (a (@ (class "oi oi-lock-locked dropdown-item")
                        (href "/admin/build/"
                              ,(assq-ref build #:id) "/restart"))
-                    "Restart"))))
+                    " Restart"))))
     (table
      (@ (class "table table-sm table-hover"))
      (tbody
@@ -516,11 +516,11 @@ system whose names start with " (code "guile-") ":" (br)
                                 (aria-expanded "false"))
                              " ")
                           (div (@ (class "dropdown-menu"))
-                               (a (@ (class "dropdown-item")
+                               (a (@ (class "oi oi-lock-locked dropdown-item")
                                      (href "/admin/evaluation/"
                                            ,(assq-ref row #:id)
                                            "/restart"))
-                                  "Restart"))))))
+                                  " Restart"))))))
                  evaluations)))))
     ,(if (null? evaluations)
          (pagination "" "" "" "")