Add pkc test (#4878)

* Add a second delay() to get the unit tests running on Rak4631

* Add test_PKC_Decrypt

* Remove cruft from test case

src/mesh/CryptoEngine.cpp

@@ -102,6 +102,7 @@ bool CryptoEngine::decryptCurve25519(uint32_t fromNode, uint64_t packetNum, size
     uint8_t *auth; // set to last 8 bytes of text?
     uint32_t extraNonce; // pointer was not really used
     auth = bytes + numBytes - 12;
+#ifndef PIO_UNIT_TESTING
     memcpy(&extraNonce, auth +8, 4); // do not use dereference on potential non aligned pointers : (uint32_t *)(auth + 8);
     LOG_INFO("Random nonce value: %d\n", extraNonce);
     meshtastic_NodeInfoLite *node = nodeDB->getMeshNode(fromNode);
@@ -115,6 +116,7 @@ bool CryptoEngine::decryptCurve25519(uint32_t fromNode, uint64_t packetNum, size
     if (!crypto->setDHKey(fromNode)) {
         return false;
     }
+#endif
     initNonce(fromNode, packetNum, extraNonce);
     printBytes("Attempting decrypt using nonce: ", nonce, 13);
     printBytes("Attempting decrypt using shared_key starting with: ", shared_key, 8);