Read, Load, Save Keys

[jeffmur]

As a user, I would like to interact with keys generated by FHE libraries.

TODO:

• [x] Save / Load Keys
• [x] Abstraction for Keys (AKey, AsealFooKey, etc.)
• [x] Validate SEAL Header for serialized strings (for saved / loaded keys)
• [x] Read Parameter Ids / Data - unique "summary"