Function parse_config_val 

fn parse_config_val(ty: &str, value: &str) -> Result<ConfigVal>

Parse a configuration value string into a ConfigVal, selecting the variant by a type tag. Each numeric/bool/duration type reuses mz_dyncfg’s own ConfigType::parse (so the accepted syntax — e.g. on/off for bool, humantime for duration — matches the rest of the codebase); string is taken verbatim.