users: Add screen reader accessible column

Current users page lists the users in a table together with a column
for actions. However, the table header doesn't include the last actions
column and instead shows the table header line ending preemptively.

As we likely don't want a visibly named column for the actions this will
instead visually just extend the line so it is consistent while also
adding a screen reader friendly text to indicate what the column is
portraying.

This does mean we need to include
`@patternfly/patternfly/patternfly-addons.css` in the PatternFly CSS
import.

pkg/lib/patternfly/patternfly-5-cockpit.scss

@@ -4,6 +4,7 @@ $pf-v5-global--fonticon-path: "patternfly-icons-fake-path";
 $pf-v5-global--disable-fontawesome: true !default; // Disable Font Awesome 5 Free
 
 @import "@patternfly/patternfly/patternfly-base.scss";
+@import "@patternfly/patternfly/patternfly-addons.css"; // Accessibility features
 
 /* Import our own fonts since the PF4 font-face rules are filtered out in build.js */
 @import "./fonts";

pkg/users/accounts-list.js

@@ -382,6 +382,7 @@ const AccountsList = ({ accounts, current_user, groups, min_uid, max_uid, shells
         { title: _("ID"), sortable: true },
         { title: _("Last active"), sortable: true },
         { title: _("Group") },
+        { title: <span className="pf-v5-u-screen-reader">{_("Actions")}</span> },
     ];
 
     const sortRows = (rows, direction, idx) => {