Translations created in Live workspace

Problem/Motivation

When a translation is added for an entity, the workspaces module will attach the translation to the default revision, and that operation will run outside of a workspace. That is problematic, because all code that reacts to the event will run its logic in the live workspace. One such example is Drupal\path\Plugin\Field\FieldType::postSave that will create a path alias in the live workspace.

Steps to reproduce

1. On a multilingual site create an unpublished node in the Live workspace
2. Create a new workspace
3. Add a manual path alias to the english/default language of the node, and publish the node
4. Add a translation for the node (language of your choice)
5. Notice that a path alias for the translated node gets created in the live workspace, not in the active workspace

Proposed resolution

Instead of attaching the translation to the main revision in the live WS, do it in the current WS.

Remaining tasks

Post a MR

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet