Description
There is no translation when we want to add CT with an existing identifier or add a field with an existing identifier

CT:

Steps to reproduce
1. Log in to BO
2. Create new CT with existing identifier e.g article
3.Try to add new field

Actual:
an error is shown, but there is a translation key instead of a message  'ez.content_type.identifier.unique'

Expect
a valid identifier uniqueness message should be displayed

Field:

Steps to reproduce
1. Log in to BO
2. Create new CT and add two field
3. Set fields identifier this same value
4. Save

Actual:
an error is shown, but there is a translation key instead of a message  'ez.field_definition.identifier.unique'

Expect
a valid identifier uniqueness message should be displayed