add: config client-error-verbosity to set error verbosity

Set error verbosity using this config. The verbosity can
be set to `verbose` or `minimal` for client error responses.

This only affects client side HTTP responses, server side logs
are not affected by this config.

Signed-off-by: Taimoor Zaeem <taimoorzaeem@gmail.com>

test/io/configs/expected/boolean-string.config

@@ -1,3 +1,4 @@
+client-error-verbosity = "verbose"
 db-aggregates-enabled = false
 db-anon-role = ""
 db-channel = "pgrst"