[IFU] Add automated issue creation workflow

[chinmaydk99]

Summary

This PR introduces an automated issue creation workflow for tracking ROCm-only commits during Integrated Fork Updates (IFU), along with enhancements to support non-main upstream source branches.

Workflows

1. create_ifu_issues.yml (New)

Creates GitHub issues for commits that exist in the ROCm fork but not in upstream. For each ROCm-only commit:

• Creates an issue with commit metadata (hash, author, branch, link)
• Assigns the commit author (via GitHub API lookup or email parsing)
• Adds the issue to a GitHub Project (V2) with custom fields (branch, commit_hash)
• Includes upstream tracking checkboxes for manual verification
• Deduplicates by commit hash to prevent duplicate issues on re-runs

2. create_ifu_tag.yml (Modified)

• Now dispatches create_ifu_issues.yml after creating IFU tags
• Resolves source_branch from PR body metadata (written by pytorch_ifu.yml)
• Supports cold-start scenarios when no previous IFU post tag exists (falls back to upstream merge-base)
• Includes a manual test harness (workflow_dispatch) with run_full_chain option for testing without real PR merges

3. pytorch_ifu.yml (Modified)

• Writes ifu_source_branch metadata to the autogenerated PR body
• Enables downstream workflows to know the exact upstream branch used for the IFU merge

Workflow run: https://github.com/ROCm/pytorch/actions/runs/23165638784

[rocm-repo-management-api]

Jenkins build for 1414296b479c09e5eb39d49f9911cdc7b4f8d10b commit finished as FAILURE
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[rocm-repo-management-api]

Jenkins build for a07efce17248d1748cb4fa1710255ff4ae93067f commit finished as FAILURE
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