Rename functions that inject key material to an allocated handle

This commit starts a migration to a new interface for key creation.
Today, the application allocates a handle, then fills its metadata,
and finally injects key material. The new interface fills metadata
into a temporary structure, and a handle is allocated at the same time
it gets filled with both metadata and key material.

This commit was obtained by moving the declaration of the old-style
functions to crypto_extra.h and renaming them with the to_handle
suffix, adding declarations for the new-style functions in crypto.h
under their new name, and running

    perl -i -pe 's/\bpsa_(import|copy|generator_import|generate)_key\b/$&_to_handle/g' library/*.c tests/suites/*.function programs/psa/*.c
    perl -i -pe 's/\bpsa_get_key_lifetime\b/$&_from_handle/g' library/*.c tests/suites/*.function programs/psa/*.c

Many functions that are specific to the old interface, and which will
not remain under the same name with the new interface, are still in
crypto.h for now.

All functional tests should still pass. The documentation may have
some broken links.

library/ssl_cli.c

@@ -3148,7 +3148,7 @@ static int ssl_write_client_key_exchange( mbedtls_ssl_context *ssl )
             return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
 
         /* Generate ECDH private key. */
-        status = psa_generate_key( handshake->ecdh_psa_privkey,
+        status = psa_generate_key_to_handle( handshake->ecdh_psa_privkey,
                           PSA_KEY_TYPE_ECC_KEYPAIR( handshake->ecdh_psa_curve ),
                           MBEDTLS_PSA_ECC_KEY_BITS_OF_CURVE( handshake->ecdh_psa_curve ),
                           NULL, 0 );