Add inter-boundary-communication-has-direction constraint

[DimitriZhurkin]

Committer Notes

Add the inter-boundary-communication-has-direction constraint, which tests the following scenario:
Every inter-boundary communication component has at least one network traffic direction property, with no more than one incoming and no more than one outgoing traffic direction property.

Related issue: #930.

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[wandmagic]

@DimitriZhurkin this needs a rebase

[DimitriZhurkin]

Closing in favor of #968.