Signing process for testing v2 policy on multi-node scenario

[haitaohuang]

Current throw-away random key used for signing v2 policy in AzCVM mode scripts can only work for single node testing. Need a signing process to for multiple node testing on real hardware.

[haitaohuang]

The live quote from underhil may change. We need capture multiple quotes to generate multiple mock quote files and use those to simulate multi-node scenarios to test policy verification/enforcement logic for different scenarios