Switch key slots to psa_key_attributes_t

Switch `psa_key_slot_t` to the full `psa_key_attributes_t`, now that this
structure only has psa_core_key_attributes_t`.

To minimize the diff without breaking the build much, temporarily make
`psa_key_attributes_t` contain either the `core` field or all the fields.
This allows both things like `slot->attr.core.type` and `slot->attr.type`
to exist. The build breaks with compilers that don't support anonymous
unions and structs, which are only standard C since C11.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/library/psa_crypto_storage.h b/library/psa_crypto_storage.h
index b6b5e15..f1ea265 100644
--- a/library/psa_crypto_storage.h
+++ b/library/psa_crypto_storage.h
@@ -93,7 +93,7 @@
  * \retval #PSA_ERROR_DATA_INVALID \emptydescription
  * \retval #PSA_ERROR_DATA_CORRUPT \emptydescription
  */
-psa_status_t psa_save_persistent_key(const psa_core_key_attributes_t *attr,
+psa_status_t psa_save_persistent_key(const psa_key_attributes_t *attr,
                                      const uint8_t *data,
                                      const size_t data_length);
 
@@ -123,7 +123,7 @@
  * \retval #PSA_ERROR_DATA_CORRUPT \emptydescription
  * \retval #PSA_ERROR_DOES_NOT_EXIST \emptydescription
  */
-psa_status_t psa_load_persistent_key(psa_core_key_attributes_t *attr,
+psa_status_t psa_load_persistent_key(psa_key_attributes_t *attr,
                                      uint8_t **data,
                                      size_t *data_length);
 
@@ -163,7 +163,7 @@
  */
 void psa_format_key_data_for_storage(const uint8_t *data,
                                      const size_t data_length,
-                                     const psa_core_key_attributes_t *attr,
+                                     const psa_key_attributes_t *attr,
                                      uint8_t *storage_data);
 
 /**
@@ -186,7 +186,7 @@
                                              size_t storage_data_length,
                                              uint8_t **key_data,
                                              size_t *key_data_length,
-                                             psa_core_key_attributes_t *attr);
+                                             psa_key_attributes_t *attr);
 
 #if defined(MBEDTLS_PSA_CRYPTO_SE_C)
 /** This symbol is defined if transaction support is required. */