Proto commits in gjbae1212/grpc-vpn

These 4 commits are when the Protocol Buffers files have changed:

Commit:0f83ee2
Author:gjbae1212

Fix a wrong name on AuthType enum struct in the protocol of GRPC.

The documentation is generated from this commit.

Commit:1c75ab4
Author:gjbae1212

Add authentication package for Google OpenID, and refactor client, server package.

Commit:5cae7e6
Author:gjbae1212

Implement methods associated with JWT and Network in the internal package.

Commit:459dede
Author:gjbae1212

Define GRPC protocol SPEC.