Improve instance dump for jail

[AlexeyAndKartashov]

mount and setns properties apply exclusively to jail data.
But in instance dump they are displayed as if they relate directly to the instance properties:

$ ubus call service list '{"name": "sysntpd"}'
{
        "sysntpd": {
                "instances": {
                        "instance1": {
                                "running": true,
                                "pid": 7405,
                                "command": [
                                        "/usr/sbin/ntpd",
                                        "-n",
                                        "-N",
                                        "-S",
                                        "/usr/sbin/ntpd-hotplug",
                                        "-p",
                                        "0.openwrt.pool.ntp.org",
                                        "-p",
                                        "1.openwrt.pool.ntp.org",
                                        "-p",
                                        "2.openwrt.pool.ntp.org",
                                        "-p",
                                        "3.openwrt.pool.ntp.org"
                                ],
                                "term_timeout": 5,
                                "respawn": {
                                        "threshold": 3600,
                                        "timeout": 5,
                                        "retry": 5
                                },
                                "no_new_privs": true,
                                "capabilities": "/etc/capabilities/ntpd.json",
                                "user": "ntp",
                                "group": "ntp",
                                "jail": {
                                        "name": "ntpd",
                                        "procfs": false,
                                        "sysfs": false,
                                        "ubus": true,
                                        "log": false,
                                        "ronly": false,
                                        "netns": false,
                                        "userns": false,
                                        "cgroupsns": false,
                                        "console": false
                                },
                                "mount": {
                                        "/bin/ubus": "0",
                                        "/usr/bin/env": "0",
                                        "/usr/bin/jshn": "0",
                                        "/usr/sbin/ntpd-hotplug": "0",
                                        "/usr/share/libubox/jshn.sh": "0"
                                }
                        }
                }
        }
}

[dangowrt]

While the pull request has a full description, the commit message itself contains only a title.
Please also include a full description in the commit message, you may (and maybe should) skip the same output.