Construct an object given the attributes and material for a PSA crypto key
and get the Mbed TLS storage representation.
The code to generate the storage representation was written based on the
specification in docs/architecture/mbed-crypto-storage-specification.md,
without looking at the code.
The data in the unit tests is from the AES-128 format_storage_data_check
test case in test_suite_psa_crypto_persistent_key.data, tweaked manually.
This commit creates a basic framework for using symbolic values for
attributes, but does not yet implement obtaining the corresponding numerical
values from an external source.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>