EZP-23317 Twig Helpers to get translatable properties

Closes #980 
Issue: https://jira.ez.no/browse/EZP-23317

Introduces 3 new Twig helpers:
- ez_field_name
- ez_field_description
- ez_trans_prop _(low level genric helper)_

See added spec for the translation helpers.

Todo:
- [x] Improve the code in terms of CS, optimization and allow use of Content + ContentInfo
- [x] Add support for getting field name ( commit by @flovntp )
- [x] Add support for getting field description
- [x] Add generic helper for translatable properties (not usable atm for FieldDefintion as mainLanguage is on ContentType only)
- [x] Unit tests
- [x] Squish commits by topics
currently nothing, but I'll update it to: throw, and change ContentExtension to catch and log (if ->log is defined). Ok?