[backend] Add samples attribute to Malware in API

[JeremyCloarec]

Proposed changes

I added "samples" to the api model of malware, so that we can properly import sample refs when importing a malware stix bundle

See also the python client PR OpenCTI-Platform/client-python#584

Related issues

• Sample ref not created when importing a bundle STIX #6275

Checklist

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

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 66.75%. Comparing base (932c5d0) to head (7448286).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #6337   +/-   ##
=======================================
  Coverage   66.74%   66.75%           
=======================================
  Files         541      541           
  Lines       64553    64555    +2     
  Branches     5306     5307    +1     
=======================================
+ Hits        43088    43093    +5     
+ Misses      21465    21462    -3     

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[SouadHadjiat]

there should be changes in the generated file graphql.ts (when I started the backend I saw these changes locally)