Feature request - Add file.capabilities (Linux)

[ahuret]

Checklist

• make test-all (UNIX) passes. CI will also test this
• unit and/or integration tests are included (if applicable)
• documentation is changed or added (if applicable)

Description of change

This is a new test feature included in file test called capabilities.
It aims to add a simple way to test for file Linux effective capabilities .
The test uses this Golang package https://github.com/syndtr/gocapability .

Usage:

file:
  my-file:
    exists: true
    capabilities:
        - 38 # CAP_PERFMON
        - 21 # CAP_SYS_ADMIN

It will test if the file has the capabilities CAP_PERFMON and CAP_SYS_ADMIN, if not the test fails.
One problem with that is to use the enum syntax to describe capabilities (see caps enums). I think it would be easier for user to write the name of the capability instead of a number but it requires to add code to transform enum in string, so I was not sure about it in term of code simplicity.

This PR is related to this issue #971 .

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📚 Documentation preview 📚: https://goss--1020.org.readthedocs.build/en/1020/