FIX: Add plural definitions for Hungarian (#27933)

Hungarian actually has a plural form (See: https://meta.discourse.org/t/issue-with-pluralized-count-translation-override/316019/8)

In a past commit we introduced an external JS library to describe the
plural form of the language. (301713ef96)
But this JS library actually has a slightly different pluralization
definition than what we use in the backend (plurals.rb). ruby-i18n
incorrectly assumes that Hungarian does not have plural forms.
This resulted in singular text being used on the front end for
Hungarian, but admins were unable to find and edit the singular text in
customization.

This commit adds a singular definition for Hungarian to the backend,
compatible with the  "make-plural/cardinals" library, thus fixing the
above issue.

config/locales/plurals.rb

@@ -42,7 +42,8 @@
   he: { i18n: { plural: { keys: [:one, :other], rule: lambda { |n| n == 1 ? :one : :other } } } },
   hi: { i18n: { plural: { keys: [:one, :other], rule: lambda { |n| [0, 1].include?(n) ? :one : :other } } } },
   hr: { i18n: { plural: { keys: [:one, :few, :other], rule: lambda { |n| n % 10 == 1 && n % 100 != 11 ? :one : [2, 3, 4].include?(n % 10) && ![12, 13, 14].include?(n % 100) ? :few : :other } } } },
-  hu: { i18n: { plural: { keys: [:other], rule: lambda { |n| :other } } } },
+  # The next line has a fix for ruby-i18n. Hungarian has plural forms. See https://meta.discourse.org/t/issue-with-pluralized-count-translation-override/316019/8
+  hu: { i18n: { plural: { keys: [:one, :other], rule: lambda { |n| n == 1 ? :one : :other } } } },
   hy: { i18n: { plural: { keys: [:one, :other], rule: lambda { |n| n == 1 ? :one : :other } } } },
   id: { i18n: { plural: { keys: [:other], rule: lambda { |n| :other } } } },
   is: { i18n: { plural: { keys: [:one, :other], rule: lambda { |n| n == 1 ? :one : :other } } } },