Gramine driver proxy and its remote executor agent

### Motivation & problem statement
This feature is associated with #525, it should be booted at the LibOS side before the workload get started. this feature is required to handle the lifecycle of agent, the remote streams access and remote attestation.

### Proposed solution
this feature needs to have the following major functions.

1) Teaclave Gramine driver proxy
2) LibOS side executor agent trait
3) To serialize FunctionArguments
4) To serialize FunctionRuntime
5) To establish a trusted channel between proxy and agent remotely with assurance
6) A protocol/service to interact with remote agent
7) control plane commands. e.g. attest, init, start, stop, destroy, custom cmds.
8) data plane: runtime streams, argument, payload