[GOVRACPROD-46] Add warning message and popup for checkbox 'Enable OpenFisca RaC integration' in webform.

[g2410g]

https://salsadigital.atlassian.net/browse/GOVRACPROD-46

Checklist before requesting a review

• I have formatted the subject to include ticket number as [#123] Verb in past tense with dot at the end.
• I have added a link to the issue tracker
• I have provided information in Changed section about WHY something was done if this was not a normal implementation
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have added tests that prove my fix is effective or that my feature works
• I have run new and existing relevant tests locally with my changes, and they passed
• I have provided screenshots, where applicable

Changed

1. Add warning message and popup for checkbox 'Enable OpenFisca RaC integration' in webform.

Screenshots

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.91%. Comparing base (841389b) to head (d52cc1d).
⚠️ Report is 1 commits behind head on 1.x.

Additional details and impacted files

@@            Coverage Diff            @@
##                1.x      #50   +/-   ##
=========================================
  Coverage     99.91%   99.91%           
- Complexity      287      288    +1     
=========================================
  Files            16       16           
  Lines          1127     1128    +1     
=========================================
+ Hits           1126     1127    +1     
  Misses            1        1           

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