Add new functions, psa_load_persistent_key(),
psa_free_persistent_key_data(), and psa_save_persistent_key(), for
managing persistent keys. These functions load to or save from our
internal representation of key slots. Serialization is a concern of the
storage backend implementation and doesn't abstraction-leak into the
lifetime management code.
An initial implementation for files is provided. Additional storage
backends can implement this interface for other storage types.
The persistent key implementation will be split across multiple
files as it will eventually be implementing multiple storage
backends. As these internal functions will need to be callable by
other files, we will add the headers in the library folder. This
commit adds this include location to the necessary scripts.
For tests, the library is added as an include location as testing
on-target with Mbed OS is not possible with paths including ".."
