Lock and encrypt state & Introduce state locking

[briancollinson]

These changes add encryption and additional protection to the state bucket, and to also require encryption when accessing/modifying state files.

Additionally, a lock table is added into dynamo with the intention of preventing multiple changes to the same state at the same type (supported by terraform and added to the backend config).

[michalschott]

Any update on this one?

[Constantin07]

Hi @briancollinson, any chance to resolve conflict please ?