* feat(tls): add an option for optional TLS client authentication
Previously there were only two options for client authentication –
either no authentication or mandatory authentication. With this change,
a server can allow for optional authentication with a given root CA
certificate and enforce client authentication on a per-request basis.
Refs: #687
* Update tonic/src/transport/server/tls.rs
---------
Co-authored-by: Lucio Franco <[email protected]>
