[Security] Use a CSPRNG for salts, tokens, and RNG seeding (#7192)

* [Security] Use a CSPRNG for salts, tokens, and RNG seeding

Password salts and activation tokens were generated with the global SFMT
RNG, which was seeded from a 32-bit timestamp, making registration
salts and activation tokens predictable. The game RNG used the same
timestamp seed across restarts.

Add CryptoUtil backed by OpenSSL RAND_bytes and use it for salt/token
generation and to seed RNG_SFMT with a 64-bit CSPRNG value in both the
client and server. Link libcockatrice_utility against OpenSSL::Crypto.

Took 30 seconds

Took 25 minutes

* Lint.

Took 4 minutes

Took 36 seconds

---------

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>

servatrice/src/main.cpp

@@ -33,6 +33,7 @@
 #include <QtGlobal>
 #include <iostream>
 #include <libcockatrice/rng/rng_sfmt.h>
+#include <libcockatrice/utility/cryptoutil.h>
 #include <libcockatrice/utility/passwordhasher.h>
 
 RNG_Abstract *rng;
@@ -169,7 +170,7 @@ int main(int argc, char *argv[])
 
     signalhandler = new SignalHandler();
 
-    rng = new RNG_SFMT;
+    rng = new RNG_SFMT(CryptoUtil::randomUInt64());
 
     std::cerr << "Servatrice " << VERSION_STRING << " starting." << std::endl;
     std::cerr << "-------------------------" << std::endl;