fix: Attempt to save ParseObject even if its nested ParseObject failed to save

[Nidal-Bakir]

New Pull Request Checklist

• I am not disclosing a vulnerability.
• I am creating this PR in reference to an issue.

Issue Description

Closes: #854

Approach

Consider the totalResponse from the batch as unsuccessful

// if any request in a batch requests group fails,
// then the overall response will be considered unsuccessful.
totalResponse.success = false;

TODOs before merging

Merge #858 first, then I will add a change log entry with that PR, so we publish two fixes in one version.(4.0.1)

• Add tests
• Add changes to documentation (guides, repository pages, in-code descriptions)
• A changelog entry

[parse-github-assistant]

Thanks for opening this pull request!

• 🎉 We are excited about your hands-on contribution!

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.19 🎉

Comparison is base (bdbc483) 26.51% compared to head (8121f62) 26.71%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #859      +/-   ##
==========================================
+ Coverage   26.51%   26.71%   +0.19%     
==========================================
  Files          47       47              
  Lines        2904     2905       +1     
==========================================
+ Hits          770      776       +6     
+ Misses       2134     2129       -5     

Impacted Files	Coverage Δ
packages/dart/lib/src/objects/parse_object.dart	90.67% <100.00%> (+2.16%)	⬆️

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[Nidal-Bakir]

The dart test will not pass because the other PR #858 has not been merged yet.

[Nidal-Bakir]

Ready to be merged.

[mtrezza]

Looks good! Waiting for CI ...