Move tests/scripts/check_names.py to the framework

[mpg]

This script has slightly diverged between development and 3.6. This task is to:

• reconcile the two branches;
• move the script to the framework;
• adapt the path everywhere the script is invoked.

Note: this task is only about mbedtls and the framework. Changes will likely be needed to adpat tf-psa-crypto; they're out of scope here and will be covered by a separate task.