New header crypto_sizes.h

This header will contain macros that calculate buffer sizes, whose
semantics are standardized but whose definitions are
implementation-specific because they depend on the available algorithms
and on some permitted buffer size tolerances.

Move size macros from crypto_struct.h to crypto_sizes.h, because these
definitions need to be available both in the frontend and in the
backend, whereas structures have different contents.

include/psa/crypto_struct.h

@@ -45,14 +45,6 @@
 #include "mbedtls/sha256.h"
 #include "mbedtls/sha512.h"
 
-#if defined(MBEDTLS_SHA512_C)
-#define PSA_HASH_MAX_SIZE 64
-#define PSA_HMAC_MAX_HASH_BLOCK_SIZE 128
-#else
-#define PSA_HASH_MAX_SIZE 32
-#define PSA_HMAC_MAX_HASH_BLOCK_SIZE 64
-#endif
-
 struct psa_hash_operation_s
 {
     psa_algorithm_t alg;