`--tls` flag just set the url scheme

[bnjjj]

When using --tls it just sets https on URL but it doesn't configure the TLS configuration properly. So it doesn't enable webpki nor root ca support. And we can't pass our custom certificates so I think this flag is kind of useless. You should enable https://docs.rs/tonic/latest/tonic/transport/channel/struct.ClientTlsConfig.html#method.with_native_roots and https://docs.rs/tonic/latest/tonic/transport/channel/struct.ClientTlsConfig.html#method.with_webpki_roots when creating your TLS configuration for tonic if the --tls flag is enabled

[lewiszlw]

Hi, Coenen, thanks for reporting this. Since we don't have tls-enabled flightsql service, we haven't verified --tls flag. Could make a pr to fix this issue and verify it in your environment?