feat(Multilingual Unit): Copy single component generates new translations

[hirokiterashima]

Changes

• Copying a single component generates new translations ids and copies over translations for the new component
• Note: to keep the scope small, I did not implement copying components via other methods.

Test

• In the node authoring view, click on the "Copy component" button for a component (not the checkbox -> copy method). This should:
  • copy the component
  • generate new translation ids for the new component (look at project.json)
  • copy the translations that were in the original component, but with new the new translation ids (look at translations.[language].json)
• Deleting components deletes translations from the translations.[language].json files as before. I extracted common code to a new EditTranslationsService class.

[geoffreykwan]

Looks good.