feat: remove flattening customData in FB Conversions and FB Pixel

[sandeepdsvs]

Description of the change

Resolves INT-925
With this change, objects and arrays in message.properties won't be flattened anymore before sending them to the destination as part of custom_data.

Type of change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Related issues

Fix #1

Checklists

Development

• Lint rules pass locally
• The code changed/added as part of this pull request has been covered with tests
• All tests related to the changed code pass in development

Code review

• This pull request has a descriptive title and information useful to a reviewer. There may be a screenshot or screencast attached
• "Ready for review" label attached to the PR and reviewers mentioned in a comment
• Changes have been reviewed by at least one other engineer
• Issue from task tracker has a link to this pull request

[codecov]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (c38f14f) 87.13% compared to head (91f78ba) 87.17%.
Report is 1 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2787      +/-   ##
===========================================
+ Coverage    87.13%   87.17%   +0.03%     
===========================================
  Files          766      766              
  Lines        28443    28469      +26     
  Branches      6655     6646       -9     
===========================================
+ Hits         24785    24818      +33     
+ Misses        3321     3314       -7     
  Partials       337      337              

Files	Coverage Δ
src/v0/destinations/facebook_pixel/transform.js	96.19% <50.00%> (-1.83%)	⬇️

... and 3 files with indirect coverage changes

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[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

44.4% Coverage
0.0% Duplication