Add a name property to BaseAttestationModel and set it for each subclass

[gproanomsft]

Problem: BaseAttestationModel did not have a way to express a descriptor of a attestation

Solution: Add an abstract property to the class that gets filled in at runtime

Validation: Unit tests updated

Type of change:

• [ x] Feature work
• [ ] Bug fix
• [ ] Documentation
• [ ] Engineering change
• [ ] Test
• [ ] Logging/Telemetry

Risk:

• [ ] High – Errors could cause MAJOR regression of many scenarios. (Example: new large features or high level infrastructure changes)
• [ ] Medium – Errors could cause regression of 1 or more scenarios. (Example: somewhat complex bug fixes, small new features)
• [ x] Small – No issues are expected. (Example: Very small bug fixes, string changes, or configuration settings changes)