Implement psa_get_key_attributes

Implement attribute querying.

Test attribute getters and setters. Use psa_get_key_attributes instead
of the deprecated functions psa_get_key_policy or
psa_get_key_information in most tests.
diff --git a/include/psa/crypto.h b/include/psa/crypto.h
index 74a36b0..e5370bf 100644
--- a/include/psa/crypto.h
+++ b/include/psa/crypto.h
@@ -140,7 +140,7 @@
 psa_status_t psa_get_key_attributes(psa_key_handle_t handle,
                                     psa_key_attributes_t *attributes);
 
-psa_status_t psa_reset_key_attributes(psa_key_attributes_t *attributes);
+void psa_reset_key_attributes(psa_key_attributes_t *attributes);
 
 /**@}*/