Store character and env variables on DSN via Auto Drive

[jfrank-summit]

From @marc-aurele-besner in #133:

To improve portability, and separate the runner from the agent itself, we could store and encrypt all the env on Auto-Drive and do the same with the character and store these CID's on the smart contract in a separate mapping.

This way the runner will only need the private key of the agent to access the config and env keys

Alternatively, the envs could be separated for what is specific to an agent (like Twitter handle and password, the private key of that agent, other social) and env that could be shared between agents using the same runner (models API keys, RPC, contract)