crypto-client: reorganize source files/folders

The goal is to keep psasim as simple as possible:

- do not build a separate lib for psa-ff; build those source
  files as part of server or client
- do not have lot of different makefiles: just 1 that does all
  we need
- do not have several subfolders for headers: only 1 is enough
  for this kind of project

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>

tests/psa-client-server/psasim/include/error_ext.h

@@ -0,0 +1,19 @@
+/* PSA status codes used by psasim. */
+
+/*
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+ */
+
+#ifndef PSA_ERROR_H
+#define PSA_ERROR_H
+
+#include <stdint.h>
+
+#include "common.h"
+
+#define PSA_ERROR_PROGRAMMER_ERROR      ((psa_status_t) -129)
+#define PSA_ERROR_CONNECTION_REFUSED    ((psa_status_t) -130)
+#define PSA_ERROR_CONNECTION_BUSY       ((psa_status_t) -131)
+
+#endif