Fix multiple chain rights assertions

[adriansmares]

Summary

This PR fixes another edge case of the AssertRights RPC, specifically the case in which the user has multiple chains of rights towards the entity. This can happen if the user is part of an organization, and the organization is also an entity collaborator, next to the user.

Changes

• Take the union of rights over all of the entity chains for an individual entity.

Testing

Local testing and unit testing.

Testing steps (as a non admin user):

1. Create an organization, associated with the user.
2. Create a gateway, associated with the user.
3. Add the organization as a collaborator to the gateway.
4. Check the gateways list in the Console. No error should occur.

Regressions

This fixes a regression caused by the fact that we use the BatchGetGatewayConnectionStats in the Console now. No extra regressions are expected.

Notes for Reviewers

I've gone again through the logic of getRights and I think this was the final difference between single entity rights assertions and batch rights assertions, but please take another sanity check.

Checklist

• Scope: The referenced issue is addressed, there are no unrelated changes.
• Compatibility: The changes are backwards compatible with existing API, storage, configuration and CLI, according to the compatibility commitments in README.md for the chosen target branch.
• Documentation: Relevant documentation is added or updated.
• The steps/process to test this feature are clearly explained including testing for regressions.
• Changelog: Significant features, behavior changes, deprecations and fixes are added to CHANGELOG.md.
• Commits: Commit messages follow guidelines in CONTRIBUTING.md, there are no fixup commits left.

[KrishnaIyer]

LGTM.