Automate creation and population of pytorch index subfolder in s3

[atalman]

Related to issue: #6097

I would like to automate the following:

1. Creation of indexes such as whl/nightly/rocm6.3/ or whl/nightly/cuda126/ with required dependencies. Source files could be previous rocm/cuda version
2. Copying of indexes with dependencies from nightly->test and from test->release when subfolder does not exist

We should be able to enable this first via https://github.com/pytorch/test-infra/blob/main/s3_management/update_dependencies.py script and later via workflow