Add bazel support and allow for objective_ template initialization

[TendTo]

This small does two main things:

• It adds Bazel support, so that other projects using Bazel wanting to use this library as a dependency can do so with ease.
• It changes the ParticleSwarmOptimization constructor slightly, so that the objective functor can be constructed on the fly
• Add a setDice method for customizing the random generator

Feel free to make any additional changes or adjustments!

Example of integrating this library in a bazel project

# MODULE.bazel

# ...

bazel_dep(name = "psocpp", version = "0.1.0")
git_override(
    module_name = "psocpp",
    commit = "commit hash or tag",
    remote = "https://github.com/Rookfighter/pso-cpp",
)

and then, in a build file

# BUILD.bazel

cc_binary(
    name = "my lib",
    srcs = ["my_main.cpp"],
    deps = ["@psocpp"],
)

Example of the new constructor

class Objective {
 public:
  Objective(const Eigen::VectorXd& offset) : offset_{offset} {}

  template <class Derived>
  double operator()(const Eigen::MatrixBase<Derived>& x) const {
    return (x.colwise() + offset_).sum();
  }

 private:
  const Eigen::VectorXd& offset_;
};

int main() {
  pso::ParticleSwarmOptimization<double, Objective2> optimiser{Eigen::VectorXd::Zero(2)};
 // ....
}