message: fix: use `localhost` as `proxy-addr` for k8s cluster on macOS
  When running `fluvio cluster start` on macOS sets `localhost` as proxy
  address by default if no other value is set. For other platforms, behavior
  remains the same as of today.
  Resolve:
diff: @@ -30,12 +30,17 @@ pub async fn process_k8(
  .chart_values(opt.k8_config.chart_values)
  .hide_spinner(false)
  .upgrade(upgrade)
  - .proxy_addr(opt.proxy_addr)
  .spu_config(opt.spu_config.as_spu_config())
  .connector_prefixes(opt.connector_prefix)
  .with_if(opt.skip_checks, |b| b.skip_checks(true))
  .use_k8_port_forwarding(opt.k8_config.use_k8_port_forwarding);
  + if cfg!(target_os = "macos") {
  + builder.proxy_addr(opt.proxy_addr.unwrap_or_else(|| String::from("localhost")));
  + } else {
  + builder.proxy_addr(opt.proxy_addr);
  + }
  +
  if let Some(chart_location) = opt.k8_config.chart_location {
  builder.local_chart(chart_location);
  }
  