i18n: improve translations across horilla (#1014)

- Added trans() / _() translations to models, forms and templates.
- Updated Spanish locale (django.po).
- Fixed missing verbose_name translations.

Known issues:
- "Leave Type" label in horilla/leave/forms.py not translating.
- "Performance" and "Mails automations" still pending.

attendance/templates/attendance/ip_restriction/ip_restriction.html

@@ -10,7 +10,7 @@
     </div>
     <div class="oh-label__info" for="application_tracking">
         <label class="oh-label fw-bold" for="application_tracking">{% trans "IP Login Restriction" %}</label>
-        <span class="oh-info mr-2" title="Enable this feature to restrict attendance marking to specific IP addresses only.">
+        <span class="oh-info mr-2" title="{% trans 'Enable this feature to restrict attendance marking to specific IP addresses only.' %}">
         </span>
         <div class="oh-switch">
             <input