Update API endpoints to handle attempt to add records that already exist
This applies to the following object types (typically added by the init scripts):
- 1 - email templates
- 2 - contact forms
- 3 - translations / labels
For 1 and 2 if an entry already exists in the database a 409 Conflict
response should be generated and the content of the database should not be modified in any way.
For 3, in case given language already exists no error should be raised, missing keys should be added with provided values, values for existing keys should be either updated or not depending on a "force" flag that should be added as well.