Add new Attestation Protocol "None" - phase 2

[johnnypham]

Summary of feature
Currently, VBS enclaves are supported on-prem and SGX enclaves on Azure VMs. VBS support for Azure is in the works but strong attestation is not possible on Azure VMs due to restrictions against accessing the host machine's Trusted Platform Module (TPM).
A new attestation protocol called "None" will be allowed in the connection string, allowing users to forgo enclave attestation when using VBS enclaves: Attestation Protocol = None

Phase 2 changes

• Attestation Protocol = None can now be added to the connection string. When this is set, the Enclave Attestation Url property is optional (it's required if Attestation Protocol is HGS or AAS).
• Attestation Protocol = None only works when the server returns an enclave type of VBS. An exception is thrown for any other enclave type.
• When using Attestation Protocol = None, the NoneAttestationEnclaveProvider will be used to set up an enclave session. This provider does not perform attestation and only derives the shared secret required to set up a secure enclave session.
• Building the driver with -p:BuildSimulator=true will still work, the driver will simply use NoneAttestationEnclaveProvider. When working with SQL Server in simulator mode, the attestation protocol should now be specified as None and not SIM.
• Tests: all of the current enclave manual tests will be run with an additional connection string using Attestation Protocol = None. Example run

[DavoudEshtehari]

/azp run

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[johnnypham]

The main purpose of having ENCLAVE_SIMULATOR directive comes from SqlConnectionAttestationProtocol.SIM which is now updated with NONE and available as a public API. I believe we can get rid of it.

#if ENCLAVE_SIMULATOR is still needed. SQL Server can run in simulator mode wherein the server will send an enclave type of SIMULATOR. When this happens, we still need the code inside those directives. For example, we still need the simulator if you want to simulate attestation with SGX enclaves, since "None" attestation won't work for SGX.