Integrate Accelerator API to intermediate_source/dist_tuto.rst

[jafraustro]

Motivation

• Enhance distributed tutorial: integrate Accelerator API for backend selection and add XCCL backend details

Description

• Integrate the Accelerator API into the intermediate_source/dist_tuto.rst to support multiple accelerators and improve backend initialization.

Checklist

• The issue that is being fixed is referred in the description (see above "Fixes #ISSUE_NUMBER")
• Only one issue is addressed in this pull request
• Labels from the issue that this PR is fixing are added to this pull request
• No unnecessary issues are included into this pull request.

cc @wconstab @osalpekar @H-Huang @kwen2501

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/tutorials/3529

• 📄 Preview Python docs built from this PR

Note: Links to docs will display an error until the docs builds have been completed.

❗ 1 Active SEVs

There are 1 currently active SEVs. If your PR is affected, please view them below:

• Multiple CI trunk failures after landing https://github.com/pytorch/pytorch/pull/161002

❌ 1 New Failure

As of commit e59b741 with merge base d54656f ():

NEW FAILURE - The following job has failed:

• Lintrunner / lintrunner (gh)
  >>> Lint for intermediate_source/dist_tuto.rst:

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[AlannaBurke]

https://docs-preview.pytorch.org/pytorch/tutorials/3529/intermediate/dist_tuto.html

Looks good to me. Make sure someone reviews the content for accuracy.