Support Custom Field module

Problem/Motivation

Editable text in a custom field → should be translated.

Steps to reproduce

• Create a custom field
• Translate a custom field using Lingotek
• Note what is and is not translated

Proposed resolution

Create a LingotekFieldProcessor for custom fields.

Remaining tasks

• Create a POC LingotekFieldProcessor for custom fields.
• Determine if the custom field module needs to declare which properties are translatable
• Determine if the lingotek module needs to declare which custom field properties are translatable
• Possibly write test coverage.

User interface changes

TBD

API changes

TDB

Data model changes

N/A