Wire individual attestation

Properly define the constant for requesting the use of device individual
attestation certificate and use it in AttestationUtils.

This lets callers to DevicePolicyManager.generateKeyPair request the use
of device-unique attestation certificate, on Keymaster implementations
that support this.

Bug: 140193672
Bug: 136494773
Test: atest com.android.cts.devicepolicy.MixedDeviceOwnerTest#testKeyManagement
Change-Id: I74de89e4c121a27b0495dcb99b0775445c3d4eaf