refactor: Rename tagline* to AppNews

[g123k]

Hi everyone!

I want to re-introduce the app review on the homepage and also the ability to inject custom info (e.g.: new country detected…).

So, now the TagLine becomes AppNews.
And the current TagLine refers to the content below the search card on the homepage.

In terms of code, there's just some renaming + some files moved:

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 2.55319% with 229 lines in your changes missing coverage. Please review.

Project coverage is 7.38%. Comparing base (4d9c7fc) to head (e9eae22).
Report is 190 commits behind head on develop.

Files	Patch %	Lines
...oth_app/lib/pages/scan/carousel/scan_carousel.dart	0.00%	84 Missing ⚠️
.../pages/scan/carousel/main_card/scan_main_card.dart	5.88%	48 Missing ⚠️
...p/lib/data_models/news_feed/newsfeed_provider.dart	10.00%	27 Missing ⚠️
...ib/pages/scan/carousel/main_card/scan_tagline.dart	0.00%	21 Missing ⚠️
...h_app/lib/data_models/news_feed/newsfeed_json.dart	0.00%	16 Missing ⚠️
..._app/lib/data_models/news_feed/newsfeed_model.dart	0.00%	15 Missing ⚠️
...lib/pages/scan/carousel/scan_carousel_manager.dart	0.00%	6 Missing ⚠️
.../smooth_app/lib/pages/navigator/app_navigator.dart	0.00%	3 Missing ⚠️
packages/smooth_app/lib/main.dart	0.00%	2 Missing ⚠️
...e_panel/knowledge_panels/knowledge_panel_page.dart	0.00%	1 Missing ⚠️
... and 6 more

Additional details and impacted files

@@            Coverage Diff             @@
##           develop   #5377      +/-   ##
==========================================
- Coverage     9.54%   7.38%   -2.17%     
==========================================
  Files          325     385      +60     
  Lines        16411   19629    +3218     
==========================================
- Hits          1567    1449     -118     
- Misses       14844   18180    +3336     

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