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.

leave/forms.py

@@ -15,7 +15,8 @@ from django.core.exceptions import ValidationError
 from django.db.models import Q
 from django.forms.widgets import TextInput
 from django.template.loader import render_to_string
-from django.utils.translation import gettext_lazy as _
+from django.utils.translation import gettext as _
+from django.utils.translation import gettext_lazy as trans
 
 from base.forms import ModelForm as BaseModelForm
 from base.methods import filtersubordinatesemployeemodel, reload_queryset
@@ -707,8 +708,8 @@ class AssignLeaveForm(HorillaForm):
             attrs={"class": "oh-select oh-select-2 mb-2", "required": True}
         ),
         empty_label=None,
-        label="Leave Type",
         required=False,
+        label=trans("Leave Type"),
     )
     employee_id = HorillaMultiSelectField(
         queryset=Employee.objects.all(),
@@ -719,7 +720,7 @@ class AssignLeaveForm(HorillaForm):
             filter_template_path="employee_filters.html",
             required=True,
         ),
-        label="Employee",
+        label=trans("Employee"),
     )
 
     def clean(self):