Features
   * Add protection for multithreaded access to the PSA keystore and protection
     for multithreaded access to the the PSA global state, including
     concurrently calling psa_crypto_init() when MBEDTLS_THREADING_C and
     MBEDTLS_THREADING_PTHREAD are defined. See
     docs/architecture/psa-thread-safety/psa-thread-safety.md for more details.
     Resolves issues #3263 and #7945.