Bug 42149: (QA follow-up) Add aria-label to shortcut nav

- Add aria-label="Quick shortcuts" to the shortcut nav element
  in both the TT include and the Vue Help component
- Ensures all nav landmarks on the staff interface are
  uniquely labeled for screen readers (WCAG 2.4.1)

To test:
- Apply the patch
- Rebuild vue components with `yarn js:build`
- Open the staff interface home page
- View the page source and confirm the shortcut nav has
  aria-label="Quick shortcuts"
- Confirm that all three nav elements (Main, Breadcrumb,
  Quick shortcuts) have unique aria-labels

Signed-off-by: Paul Derscheid <paul.derscheid@lmscloud.de>
Signed-off-by: Martin Renvoize <martin.renvoize@openfifth.co.uk>

koha-tmpl/intranet-tmpl/prog/en/includes/shortcut.inc

@@ -1,4 +1,4 @@
-<nav id="shortcut" class="shortcut">
+<nav id="shortcut" class="shortcut" aria-label="Quick shortcuts">
     [% IF Koha.Preference('showLastPatron') %]
         [% INCLUDE 'last-borrower.inc' %]
     [% END %]

koha-tmpl/intranet-tmpl/prog/js/vue/components/Help.vue

@@ -1,5 +1,5 @@
 <template>
-    <nav id="shortcut" class="shortcut">
+    <nav id="shortcut" class="shortcut" :aria-label="$__('Quick shortcuts')">
         <a
             href="/cgi-bin/koha/help.pl"
             class="toplinks"