[backend/frontend] prevent delete CSV mappers if used by CSV ingesters (#6757)

[labo-flg]

Proposed changes

• when user deletes a CSV mapper, find and delete all csv ingesters that uses it.
• add warning about feeds being deleted as part of the cascade deletion, in the confirm popover
• fix bad form validation and reset in IngestionCsvCreation

Related issues

• closes #6757

Checklist

• [x] I consider the submitted work as finished
• [x] I tested the code for its functionality
• [x] I wrote test cases for the relevant uses case (coverage and e2e)
• [ ] I added/update the relevant documentation (either on github or on notion)
• [x] Where necessary I refactored code to improve the overall quality

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 72.00000% with 7 lines in your changes are missing coverage. Please review.

Project coverage is 67.41%. Comparing base (64d087e) to head (08c5fa5).

Files	Patch %	Lines
...rm/opencti-graphql/src/utils/migration-template.js	0.00%	7 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6891      +/-   ##
==========================================
- Coverage   67.42%   67.41%   -0.01%     
==========================================
  Files         561      561              
  Lines       68510    68533      +23     
  Branches     5713     5713              
==========================================
+ Hits        46191    46200       +9     
- Misses      22319    22333      +14     

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[labo-flg]

Back to draft: need to add a migration script to fix ingesters that might have lost their mapper.