[client] handle file markings in file export (opencti #11643)

[JeremyCloarec]

Proposed changes

• file markings weren't exported when exporting entity

octi PR https://github.com/OpenCTI-Platform/opencti/pull/12666

Related issues

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

Further comments

If this is a relatively large or complex change, kick off the discussion by explaining why you chose the solution you did and what alternatives you considered, etc...