chore: NewsProvider - Allow the URL of a translated image to be null

[g123k]

Hi everyone,

Here is a small improvement for the tagline/news, to allow empty URL on translated images.
It will reduce the size of the JSON.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 9 lines in your changes missing coverage. Please review.

Project coverage is 7.18%. Comparing base (4d9c7fc) to head (d4c585c).
Report is 229 commits behind head on develop.

Files	Patch %	Lines
...h_app/lib/data_models/news_feed/newsfeed_json.dart	0.00%	7 Missing ⚠️
...ib/pages/scan/carousel/main_card/scan_tagline.dart	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           develop   #5446      +/-   ##
==========================================
- Coverage     9.54%   7.18%   -2.37%     
==========================================
  Files          325     391      +66     
  Lines        16411   20384    +3973     
==========================================
- Hits          1567    1464     -103     
- Misses       14844   18920    +4076     

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