fix: in initFlowUrl carry over login challenge

[jonas-jonas]

Related Issue or Design Document

Checklist

• I have read the contributing guidelines and signed the CLA.
• I have referenced an issue containing the design document if my change introduces a new feature.
• I have read the security policy.
• I confirm that this pull request does not address a security vulnerability.
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• I have added tests that prove my fix is effective or that my feature works.
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Further comments

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 42.21%. Comparing base (f3fad4d) to head (d45330a).
Report is 27 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #347      +/-   ##
==========================================
- Coverage   42.43%   42.21%   -0.22%     
==========================================
  Files         136      138       +2     
  Lines        2008     2106      +98     
  Branches      288      313      +25     
==========================================
+ Hits          852      889      +37     
- Misses       1149     1205      +56     
- Partials        7       12       +5     

Components	Coverage Δ
@ory/elements-react	37.00% <31.35%> (+0.21%)	⬆️
@ory/nextjs	64.33% <74.24%> (-1.65%)	⬇️