Improve data validation for app native auth response

[janakamarasena]

Previous there were no authenticators that sent additional data without any required params. But with the introduction of push based authentication since the actual authentication happens in a decoupled manner the auth request for push auth doesn't have any required params. However the push authenticator needs to transmit additional data.

[jenkins-is-staging]

PR builder started
Link: https://github.com/wso2/product-is/actions/runs/12945394827

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 55.48%. Comparing base (72b70c8) to head (299dbdf).

Files with missing lines	Patch %	Lines
...ntity/oauth/endpoint/api/auth/ApiAuthnHandler.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #2690      +/-   ##
============================================
+ Coverage     55.34%   55.48%   +0.13%     
+ Complexity     8668     8494     -174     
============================================
  Files           647      647              
  Lines         50709    49798     -911     
  Branches       9956     9648     -308     
============================================
- Hits          28063    27628     -435     
+ Misses        18589    18180     -409     
+ Partials       4057     3990      -67     

Flag	Coverage Δ
unit	39.50% <0.00%> (-0.09%)	⬇️

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[jenkins-is-staging]

PR builder completed
Link: https://github.com/wso2/product-is/actions/runs/12945394827
Status: failure