Implement PR Issue Checker Workflow

[smog-root]

Description: We need to create a GitHub Actions workflow that automates the validation of pull requests (PRs). This workflow will ensure that all PRs meet the following criteria before being merged:

PR Description Check: Every PR must have a description. If the description is missing, the PR should fail the check.

Issue Reference Check: The PR description must include an issue reference in the format Fixes #. If the PR is not addressing an existing issue, it should mention Fixes #NEW as a placeholder.

Acceptance Criteria:

• A GitHub Action workflow is triggered on PR events (opened, edited).

The workflow checks the PR body for:

• A non-empty description.
• The presence of Fixes # or Fixes #NEW.

If the criteria are not met:

• The workflow should fail and return clear error messages.

If the checks pass:

• A confirmation message is outputted.

Expected Output:

• Error message if the PR description is missing.
• Error message if the issue reference is missing or incorrectly formatted.
• Success message when all checks are satisfied.

Additional Notes:

• This issue may serve as a foundation for more advanced PR validation (e.g., commit message format, label enforcement).
• We can later extend this to check for specific branch naming conventions or enforce the addition of specific labels.

Note: i'm expecting a gssoc-ext with level3 (or) level2 and a hacktoberfest-accepted label!

@ayush-that