Language variables dialog with entries field

[distantnative]

Description

Summary of changes

• Language variable dialog uses entries field

- Fixed immutable bug in `LanguageVariable::create()`

Additional context

• I suggest we skip adding unit tests for the area dialog code (and add unit tests as soon as we refactor this code into proper UI dialog classes)
• Replaces Support creating/editing array language variables with using new entries field #7011

Changelog

Feature

• Language variables with multiple translation strings (for different counts) can now be edited in the Panel using the new entries field

Ready?

• In-code documentation (wherever needed)
• Unit tests for fixed bug/feature
• Tests and CI checks all pass

For review team

• Add lab and/or sandbox examples (wherever helpful)
• Add changes & docs to release notes draft in Notion

[bastianallgeier]

It works great. It would of course be nice, if we could add the index number (0, 1, 2+) as help text somehow to each entry. But I think it's understandable enough for now.

I agree about the test coverage. Do we want to actively ignore it code comments or simply merge it?

[distantnative]

I would just merge it.