fix: Incorrect results when ParseQuery contains special characters

[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: #841

Approach

use Uri.encodeComponent(URLComponent);

This will produce an encoded query value:
?where={"Name":"AB%2BAB"}
The encoded equivalent of:
?where={"Name": "AB+AB"}

TODOs before merging

• 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: 85.71% and project coverage change: +0.98 🎉

Comparison is base (4e4bfab) 38.51% compared to head (b0a8901) 39.50%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #866      +/-   ##
==========================================
+ Coverage   38.51%   39.50%   +0.98%     
==========================================
  Files          60       60              
  Lines        3331     3339       +8     
==========================================
+ Hits         1283     1319      +36     
+ Misses       2048     2020      -28     

Impacted Files	Coverage Δ
packages/dart/lib/src/network/parse_query.dart	45.07% <85.71%> (+12.65%)	⬆️

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[Nidal-Bakir]

I will await for my other PR (#860) to be merged to see all the added tests and changes.

[Nidal-Bakir]

@parse-community/flutter-sdk-review

This is ready.

[mbfakourii]

Everything looks good

[mtrezza]

Looks good!