Migrate Minogrpc security mechanisms to Minows

[pierluca]

Context

Minows was developed by @XioZ and @ineiti as a more robust Mino implementation than MinoGRPC.

However, Minows currently lacks the security features needed to fully replace MinoGRPC, including a secure mechanism to connect nodes (the first time) based on secret tokens, and certificate-based node authentication.

Refer to the MinoGRPC server tests to see the expected functionality regarding joins, cert chains and tokens.

Outcomes

When this is implemented, minogrpc can be deprecated and replaced in all use cases.
We will then be able to close tickets #150, #170, #180, #218 and #220.

[ineiti]

A more simple way to finalize this is to put a big warning on it:

Minows should only be used behind a TLS terminator like traefik

That would solve all these problems, but put the trust in the TLS terminator. And there you could either use your own certificates or use the global CAs...