[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

Dockerfile

@@ -14,6 +14,7 @@ RUN apt-get update \
       libmariadb-dev-compat \
       libprotobuf-dev \
       libqt6sql6-mysql \
+      libssl-dev \
       qt6-websockets-dev \
       protobuf-compiler \
       qt6-tools-dev \
@@ -42,6 +43,7 @@ RUN apt-get update \
       libprotobuf32t64 \
       libqt6sql6-mysql \
       libqt6websockets6 \
+      libssl3 \
     && apt-get clean \
     && rm -rf /var/lib/apt/lists/*