[1.x] Implement Support for Translatable Validation Attribute Errors …

…(#4070)

* chore: add validation translations

* feat: implement ability to translate validation attributes

* chore: change translation key

* style: formatting

* perf: cache `getAttributeNames`

* perf: cache `getAttributeNames`

* chore

* style: formatting

locale/en.yml

@@ -127,3 +127,13 @@ flarum-tags:
     choose_tags_placeholder: "{count, plural, one {Choose 1 more tag} other {Choose # more tags}}"
     name: Name
     tags: Tags
+
+  validation:
+    attributes:
+      name: name
+      slug: slug
+      is_hidden: hidden
+      description: description
+      color: color
+      tag_count_primary: => validation.attributes.tag_count_primary
+      tag_count_secondary: => validation.attributes.tag_count_secondary