feat: add YAML support to server (#6934)

cli/testdata/coder_server_--help.golden

@@ -57,6 +57,16 @@ Clients include the coder cli, vs code extension, and the web UI.
       --ssh-hostname-prefix string, $CODER_SSH_HOSTNAME_PREFIX (default: coder.)
           The SSH deployment prefix is used in the Host of the ssh config.
 
+Config Options 
+Use a YAML configuration file when your server launch become unwieldy.
+
+  -c, --config yaml-config-path, $CODER_CONFIG_PATH
+          Specify a YAML file to load configuration from.
+
+      --write-config bool
+          
+          Write out the current server config as YAML to stdout.
+
 Introspection / Logging Options 
       --log-human string, $CODER_LOGGING_HUMAN (default: /dev/stderr)
           Output human-readable logs to a given file.