New elliptic curve family: twisted Edwards

Add an elliptic curve family for the twisted Edwards curves
Edwards25519 and Edwards448 ("Goldilocks"). As with Montgomery curves,
since these are the only two curves in common use, the family has a
generic name.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

scripts/mbedtls_dev/crypto_knowledge.py

@@ -78,6 +78,7 @@ class KeyType:
         'PSA_ECC_FAMILY_SECT_R2': (163,),
         'PSA_ECC_FAMILY_BRAINPOOL_P_R1': (160, 192, 224, 256, 320, 384, 512),
         'PSA_ECC_FAMILY_MONTGOMERY': (255, 448),
+        'PSA_ECC_FAMILY_TWISTED_EDWARDS': (256, 448),
     }
     KEY_TYPE_SIZES = {
         'PSA_KEY_TYPE_AES': (128, 192, 256), # exhaustive