feat: add basic token authentication between server and clients

[Manuthor]

Authenticated mode

In authenticated mode, the server requires authentication for all requests. The authentication
method can be either (one of them is enough):

• a TLS client certificate and the server extracts the username from the certificate's subject
  common name (CN)
• or a JWT access token and the server extracts the username from the token's subject (sub) claim
• an API token passed in the Authorization header configured both at the client and server side (user being default-username)

The server can be configured to use multiple authentication methods concurrently:

• if server is started with TLS client certificate authentication, client MUST provide a valid certificate issued by the authority certificate provided by the server ;
• if server only provides JWT and API token authentication, client MUST provide a valid JWT token or an API token in the Authorization header. Server will first try to authenticate using the JWT token, then the API token if JWT token is not provided.