Display draft HIPs for Jekyll build

[mgarbs]

Description:
This PR adds a GitHub Action that automatically collects data about open pull requests containing HIPs drafts. Key features:

• Runs every 6 hours on the main branch
• Queries GitHub's GraphQL API to fetch open PRs from the repository
• Stores PR data in _data/draft_hips.json for use by the site
• Uses GitHub's built-in token for authentication
• Includes error handling and automatic commit skipping when no changes detected

This automation replaces the current client-side GitHub API calls, which:

• Removes the need for storing GitHub tokens in the site
• Prevents rate limiting issues
• Improves page load performance by using pre-fetched data

The workflow generates a JSON file containing PR metadata including:

• PR number, title, and URL
• Author information
• File changes
• Reference IDs needed for content fetching

Testing

• Workflow has been tested in a fork environment
• Successfully fetches all open PRs
• Correctly identifies and processes markdown files
• Properly commits and updates data file

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[sergmetelin]

LGTM

[nathanklick]

The only thing I would suggest is using SHA hashes for the actions steps instead of v3 etc.

This is a GHA best practice.