[Server] ValidateRolePermissions of MonitoredItems based of the saved user identity to allow validation when no session is present

Proposed changes

Extend IMonitoredItem Interface to allow the access to the savedUserIdentity of the owning Subscription.

This allows the MonitoredNode to validate the RolePermissions of the owning user of the MI to decide if reading the value /event is allowed.

[] Bugfix (non-breaking change which fixes an issue)
[ ] Enhancement (non-breaking change which adds functionality)
[ ] Test enhancement (non-breaking change to increase test coverage)
x ] Breaking change (fix or feature that would cause existing functionality to not work as expected, requires version increase of Nuget packages)
[ ] Documentation Update (if none of the other choices apply)

[x] I have read the CONTRIBUTING doc.
[x] I have signed the CLA.
[ ] I ran tests locally with my changes, all passed.
[ ] I fixed all failing tests in the CI pipelines.
[ ] I fixed all introduced issues with CodeQL and LGTM.
[ ] I have added tests that prove my fix is effective or that my feature works and increased code coverage.
[ ] I have added necessary documentation (if appropriate).
[ ] Any dependent changes have been merged and published in downstream modules.