CLOUDP-253160: License header check

[helderjs]

Summary

This PR adds a license header to project files and also a check step on CI workflow

Proof of Work

There a new check add to the workflow, PR should fail CI when header is missing

Checklist

• Have you linked a jira ticket and/or is the ticket in the title?
• Have you checked whether your jira ticket required DOCSP changes?
• Have you checked for release_note changes?
• Have you signed our CLA?

Reminder (Please remove this when merging)

• Please try to Approve or Reject Changes the PR, keep PRs in review as short as possible
• Remember the following Communication Standards - use comment prefixes for clarity:
  • blocking: Must be addressed before approval.
  • follow-up: Can be addressed in a later PR or ticket.
  • q: Clarifying question.
  • nit: Non-blocking suggestions.
  • note: Side-note, non-actionable. Example: Praise
  • --> no prefix is considered a question