Use native buttons instead of links

- link with no href is not focusable
- button handle natively space and enter

Author: trasher

css/includes/components/_global-menu.scss

@@ -60,7 +60,7 @@
 .topbar {
     #navbar-menu {
         .nav-item {
-            a.nav-link {
+            .nav-link {
                 color: var(--glpi-mainmenu-fg);
 
                 &:hover {
@@ -69,7 +69,7 @@
             }
 
             &:not(.active) {
-                a.nav-link {
+                .nav-link {
                     opacity: 0.7;
                 }
             }

templates/layout/parts/menu.html.twig

@@ -50,13 +50,14 @@
    {% endif %}
    {% if has_subitems %}
    <li class="nav-item dropdown {{ firstlevel_active ? 'active' : '' }}" aria-label="{{ firstlevel['title'] }}">
-      <a class="nav-link dropdown-toggle {{ firstlevel_active ? 'active' : '' }} {{ firstlevel_shown ? 'show' : '' }}"
-         data-bs-toggle="dropdown" role="button"
+      <button type="button"
+         class="nav-link dropdown-toggle {{ firstlevel_active ? 'active' : '' }} {{ firstlevel_shown ? 'show' : '' }}"
+         data-bs-toggle="dropdown"
          data-testid="sidebar-menu-toggle"
          aria-expanded="{{ firstlevel_shown ? 'true' : 'false' }}">
          <i class="{{ firstlevel['icon'] ?? '' }}"></i>
          <span class="menu-label">{{ firstlevel['title'] }}</span>
-      </a>
+      </button>
       <div class="dropdown-menu {{ firstlevel_active and is_vertical != false ? '' : 'animate__animated' }} {{ is_vertical ? 'animate__fadeInLeft' : 'animate__zoomIn' }} {{ firstlevel_shown ? 'show' : '' }}">
          <h6 class="dropdown-header">{{ firstlevel['title'] }}</h6>
          <div class="dropdown-menu-columns">