Test the block size for symmetric keys

Also insist on their category.

Fix a missing implementation of PSA_BLOCK_CIPHER_BLOCK_SIZE for
ChaCha20.
diff --git a/tests/scripts/test_psa_constant_names.py b/tests/scripts/test_psa_constant_names.py
index 585f9de..717d0db 100755
--- a/tests/scripts/test_psa_constant_names.py
+++ b/tests/scripts/test_psa_constant_names.py
@@ -102,6 +102,8 @@
             # Any function ending in _algorithm also gets added to
             # self.algorithms.
             'key_type': [self.key_types],
+            'block_cipher_key_type': [self.key_types],
+            'stream_cipher_key_type': [self.key_types],
             'ecc_key_types': [self.ecc_curves],
             'dh_key_types': [self.dh_groups],
             'hash_algorithm': [self.hash_algorithms],