[Improvement] Use Constant Types Instead of Individual Enum Validations in internal/relay/conf/cfg.go

[ioogle]

filepath: internal/relay/conf/cfg.go

func (r *Config) validateType() error {
    if r.ListenType != constant.RelayTypeRaw &&
        r.ListenType != constant.RelayTypeWS &&
        r.ListenType != constant.RelayTypeMWS &&
        r.ListenType != constant.RelayTypeWSS &&
        r.ListenType != constant.RelayTypeMTCP &&
        r.ListenType != constant.RelayTypeMWSS {
        return fmt.Errorf("invalid listen type:%s", r.ListenType)
    }

    if r.TransportType != constant.RelayTypeRaw &&
        r.TransportType != constant.RelayTypeWS &&
        r.TransportType != constant.RelayTypeMWS &&
        r.TransportType != constant.RelayTypeWSS &&
        r.TransportType != constant.RelayTypeMTCP &&
        r.TransportType != constant.RelayTypeMWSS {
        return fmt.Errorf("invalid transport type:%s", r.ListenType)
    }
    return nil
}

[Ehco1996]

pr is welcome