Add Data Format Validation CI/CD Workflow

[vsvaidya27]

Description

This PR adds an automated data format validation workflow that runs on all PRs targeting the main branch. The workflow helps maintain data quality and consistency across all BFCL JSON files.

What's Added

• New GitHub Actions workflow: .github/workflows/bfcl_data-format-check.yml
• Python validation script: berkeley-function-call-leaderboard/scripts/validate_data_format.py

How It Works

1. The workflow triggers automatically when:

   • A PR is opened/updated targeting the main branch
   • Changes are made to JSON files in berkeley-function-call-leaderboard/data/

2. The validation script:

   • Checks all BFCL_v3 JSON files against their respective schemas
   • Validates different file types (multi_turn, sql, chatable, etc.)
   • Ensures required fields and correct data types
   • Generates detailed validation reports

3. The workflow bot:

   • Comments on the PR with validation results
   • Shows ✅ success or ❌ failure status
   • Lists any validation errors with specific details
   • Blocks PR merging if validation fails

Testing Done

• Tested with various file types
• Verified error reporting
• Confirmed bot comments functionality