MVVM implementation for News Article Page (news_article.dart).

[rutvik11062000]

Is your feature request related to a problem? Please describe.
This is the child issue of #758
To implement MVVM architecture on news_article.dart file.

Describe the solution you'd like
See #760 for in-depth details about the implementation.
For Sample see the PR changes #759

Additional context
Other things to take into consideration:

1. Make sure all the files that you are either updating or creating must be under 300 lines.
2. If there are multiple same widget with only few modification extract it as a method and give only change variable as a parameter.
3. Make the code as concise as possible.
4. Kindly create test file and add the tests.

[StrangeNoob]

@Sagar2366 if @rutvik11062000 wont mind then I would I like to work on this

[rutvik11062000]

Sure @StrangeNoob you can work on this if sir permits😊.