Make shipping plugin fields translations configurable independently

Problem/Motivation

This is a follow-up of #[2934142]. It would be great to have the configuration a shipping method plugin provides translatable independently. One example: Usually the same shipping rates apply regardless of the translation, but the rate label and description should be translatable. Since the Plugin field can only be completely translated, we have to maintain the shipping rates for each language.

There is a comment about this issue here: https://www.drupal.org/project/commerce_shipping/issues/2934142#comment-... ✨ Shipping method entity does not support translations Fixed

Steps to reproduce

• Enable translation on the shipping method entity
• Create and translate a shipping method with the flat_rate plugin
• The rates can be changed independently in the translations

Proposed resolution

We want to have each plugin configuration translatability to be configurable separately.

Remaining tasks

TBD

User interface changes

TBD

API changes

TBD

Data model changes

TBD