Did integration and fixes in AR

[wistefan]

Proposed changes

The changes allow the usage of certificates as defined by gaia-x for the i4Trust functionality. Beside that, it makes the policy-implementation more compliant with the iShare-Spec(e.g. attributes and identifiers are not longer mandatory).

Types of changes

What types of changes does your code introduce to the project: Put an x in the boxes that apply

• [x] Bugfix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

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• [x] I have read the CONTRIBUTING doc
• [x] I have signed the CLA
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] I have added necessary documentation (if appropriate)
• [ ] Any dependent changes have been merged and published in downstream modules

Further comments

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