misc: add trigram index on unaccented role names (#87906)

src/authentic2/manager/forms.py

@@ -405,7 +405,7 @@ class ServiceRoleSearchForm(CssClass, PrefixFormMixin, FormWithRequest):
             for word in (w.strip() for w in self.cleaned_data.get('text').split(' ')):
                 if not word:
                     continue
-                qs = qs.filter(name__unaccent__icontains=word)
+                qs = qs.filter(name__immutable_unaccent__icontains=word)
         if not app_settings.SHOW_INTERNAL_ROLES and not self.cleaned_data.get('internals'):
             qs = qs.exclude(slug__startswith='_')
         return qs

src/authentic2/utils/lookups.py

@@ -1,4 +1,5 @@
 from django.contrib.postgres.lookups import Unaccent as PGUnaccent
+from django.db.models import CharField, TextField, Transform
 from django.db.models.functions import Concat
 from django.db.models.functions import ConcatPair as DjConcatPair
 
@@ -7,6 +8,16 @@ class Unaccent(PGUnaccent):
     function = 'immutable_unaccent'
 
 
+class UnaccentTransform(Transform):
+    bilateral = True
+    lookup_name = 'immutable_unaccent'
+    function = 'immutable_unaccent'
+
+
+CharField.register_lookup(UnaccentTransform)
+TextField.register_lookup(UnaccentTransform)
+
+
 class ConcatPair(DjConcatPair):
     """Django ConcatPair does not implement as_postgresql, using CONCAT as a default.