feat: add support for identity stitching for shopify pixel flow

[yashasvibajpai]

What are the changes introduced in this PR?

Using clientId from pixel events, to be used as anonymousId for events in server and pixel both, and mapped to the cartToken in redis for identity stitching.

What is the related Linear task?

Resolves INT-2728

Please explain the objectives of your changes below

Put down any required details on the broader aspect of your changes. If there are any dependent changes, mandatorily mention them here

Any changes to existing capabilities/behaviour, mention the reason & what are the changes ?

N/A

Any new dependencies introduced with this change?

N/A

Any new generic utility introduced or modified. Please explain the changes.

N/A

Any technical or performance related pointers to consider with the change?

N/A

@coderabbitai review

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Developer checklist

• My code follows the style guidelines of this project

• No breaking changes are being introduced.

• All related docs linked with the PR?

• All changes manually tested?

• Any documentation changes needed with this change?

• Is the PR limited to 10 file changes?

• Is the PR limited to one linear task?

• Are relevant unit and component test-cases added in new readability format?

Reviewer checklist

• Is the type of change in the PR title appropriate as per the changes?

• Verified that there are no credentials or confidential data exposed with the changes.

[codecov]

Codecov Report

Attention: Patch coverage is 96.87500% with 1 line in your changes missing coverage. Please review.

Project coverage is 89.01%. Comparing base (31a963f) to head (7a8ffcf).
Report is 2 commits behind head on develop.

Files with missing lines	Patch %	Lines
src/v1/sources/shopify/pixelTransform.js	96.42%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #3818   +/-   ##
========================================
  Coverage    89.00%   89.01%           
========================================
  Files          609      609           
  Lines        32872    32901   +29     
  Branches      7765     7768    +3     
========================================
+ Hits         29259    29287   +28     
- Misses        3300     3331   +31     
+ Partials       313      283   -30     

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[devops-github-rudderstack]

Test report for this run is available at: https://test-integrations-dev.s3.amazonaws.com/integrations-test-reports/rudder-transformer/3818/test-report.html

[sonarqubecloud]

Quality Gate passed

Issues
17 New issues
1 Accepted issue

Measures
0 Security Hotspots
92.9% Coverage on New Code
0.3% Duplication on New Code

See analysis details on SonarCloud