Implement auto-serialization

[rubuy-74]

Closes #662.
Continues the work started in #837.

Review checklist

• Terms and conditions reflect the current change
• Contains enough appropriate tests
• If aimed at production, writes a new summary in whatsnew/whatsnew-pt-PT
• Properly adds an entry in changelog.md with the change
• If PR includes UI updates/additions, its description has screenshots
• Behavior is as expected
• Clean, well-structured code

[codecov]

Codecov Report

Attention: Patch coverage is 13.04348% with 100 lines in your changes missing coverage. Please review.

Project coverage is 16%. Comparing base (aed0bfc) to head (a53c0e9).
Report is 2 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff           @@
##           develop   #1072   +/-   ##
=======================================
+ Coverage       16%     16%   +1%     
=======================================
  Files          233     234    +1     
  Lines         7293    7235   -58     
=======================================
+ Hits          1139    1140    +1     
+ Misses        6154    6095   -59     

[thePeras]

Not looking into the code now, I noticed the amount of files generated by the package.
We can reduce into one .g.dart file if we follow this approach with a _models.dart file.

Declarate a library with the json annotation import as well all the parts of all of the models and in each model file include part of <library_name>;
Running the command again, will generate only one _models.g.dart file.

Feel free to follow or not this idea.

[bdmendes]

I didn't have the chance to test this properly, but looking at the code seems all fine!

[bdmendes]

I'm getting this error in my account:

Does this help?

[bdmendes]

@rubuy-74 can you rebase this?

[LuisDuarte1]

Good work, please fix the linting and address some issues below 🚀

Non-active member.

Urgency on changes