The release script must be run from mbed-os root, otherwise the test
partition binaries will not be created. Add a note in the tool's README
to make this clear and hopefully help save someone some debugging time
in the future.
* Unify PSA generators
* Replace scanning for mbed_spm templates with json
* Make generate_source_files and parse_manifests common
* Make assert_int an internal function
* Use parse_manifests in pytests
* Update docs