[Bug] unify get_ip methods and netifaces missing

[jimmy-evo]

Checklist

• 1. I have searched related issues but cannot get the expected help.
• 2. The bug has not been fixed in the latest version.
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Describe the bug

ImportError: Environment variable SGLANG_LOCAL_IP_NIC requires package netifaces, please install it through 'pip install netifaces'

Reproduction

PD with mooncake, set Environment variable SGLANG_LOCAL_IP_NIC

Environment

docker sglang:v0.5.0rc0-cu126

[jimmy-evo]

related PR:
#8356 why remove pip install netifaces
#7237 (comment)
@fzyzcjy
I prefer to install netifaces in docker image (not write in project.toml), or i have to maintain another branch to install this.

also, https://github.com/SamuelYvon/netifaces-2 is an alternative

@ShangmingCai there are too many duplicate and similar get_ip_xxx
get_local_ip_auto can get ip with SGLANG_HOST_IP in get_ip()

and get_ip do the same thing as def get_local_ip_by_remote() -> str:

[jimmy-evo]

I would like to submit a PR.
I'd also like to hear your opinions.