The following provides more information on this PR:
- PSA stands for Platform Security Architecture.
- Add support for use of psa_trusted_storage_api internal_trusted_storage.h v1.0.0
as the interface to the psa_trusted_storage_linux backend (i.e. for persistent
storage when MBEDTLS_PSA_ITS_FILE_C is not defined). This requires changes
to psa_crypto_its.h and psa_crypto_storage.c to migrate to the new API.
Merge storage_common.h and internal_trusted_storage.h into a single
file for convenience.
Remove #include of <psa/error.h> which crypto doesn't have yet and
include <psa/crypto_types.h> and <psa/crypto_values.h> instead.
Drop __cplusplus support which we don't need.
Tweak style (whitespace, line breaks, comment formatting) to satisfy
check-names.sh and check-files.sh.