[Feature Request]: EXTRA_INDEX_URL env var for pip

[AR2000AR]

Is there an existing issue for this?

• I have searched the existing issues and checked the recent builds/commits

What would your feature do ?

It would be nice to have a EXTRA_INDEX_URL environment variable like the INDEX_URL environment var used in modules/launch_utils.py to set the pip --extra-index-url argument.

Alternative : Deprecate INDEX_URL and document using the pip env vars PIP_INDEX_URL and PIP_EXTRA_INDEX_URL

Proposed workflow

Set the EXTRA_INDEX_URL to something like https://download.pytorch.org/whl/rocm6.2.4
Run launch.py and let it install requirements using the extra index url and the default implicit one

Additional information

https://pip.pypa.io/en/stable/cli/pip_install/#cmdoption-extra-index-url