SHA hardware allows each of SHA1, SHA256, SHA384&SHA512 to calculate digests
concurrently.
Currently incompatible with AES acceleration due to a hardware reset problem.
Ref TW7111.
Default esp-idf builds now show -Wextra warnings (except for a few:
signed/unsigned comparison, unused parameters, old-style C declarations.)
CI building of examples runs with that level raised to -Werror, to catch
those changes going into the main repo.
