1. Supporting `SIOCSIFADDR` and `SIOCDIFADDR` with Linux in6_ifreq struct to manage ipv6 addresses.
Ref: https://man7.org/linux/man-pages/man7/netdevice.7.html
2. Supporting alias like 'eth0:0' for multiple IPv6 addresses, to keep previous ioctl `SIOCGLIFADDR`, `SIOCSLIFADDR`, `SIOCGLIFNETMASK` and `SIOCSLIFNETMASK` working.
Ref: https://man7.org/linux/man-pages/man8/ifconfig.8.html
Signed-off-by: Zhe Weng <wengzhe@xiaomi.com>