[Backport 3.6] Move check_files.py to the framework

[eleuzi01]

Description

Resolves Mbed-TLS/mbedtls-framework#72

PR checklist

Please remove the segment/s on either side of the | symbol as appropriate, and add any relevant link/s to the end of the line.
If the provided content is part of the present PR remove the # symbol.

• changelog provided | not required because:
• development PR provided Move check_files.py to the framework #9800
• framework PR provided Move check_files.py to the framework mbedtls-framework#84
• 3.6 PR provided
• 2.28 PR not required
• tests not required

Notes for the submitter

Please refer to the contributing guidelines, especially the
checklist for PR contributors.

Help make review efficient:

• Multiple simple commits
  • please structure your PR into a series of small commits, each of which does one thing
• Avoid force-push
  • please do not force-push to update your PR - just add new commit(s)
• See our Guidelines for Contributors for more details about the review process.

[minosgalanakis]

LGTM