Add assign action

[nahueespinosa]

Proposed changes

View-action composition in the range library is limited. This patch implements a new range adaptor object that can be appended to any view closure to evaluate it eagerly and assign the result to a given range, effectively converting any view into an action.

Related to #279.

The simple particle filter pipeline example becomes:

struct Particle {
  int state;
  double weight;
};

auto particles = std::vector<Particle>{};
auto motion_model = ...;
auto sensor_model = ...;

particles |= beluga::actions::propagate(motion_model) |
             beluga::actions::reweight(sensor_model) |
             beluga::views::sample |
             ranges::views::take_exactly(1000) |
             beluga::actions::assign;

Type of change

• 🐛 Bugfix (change which fixes an issue)
• 🚀 Feature (change which adds functionality)
• 📚 Documentation (change which fixes or extends documentation)

Checklist

• Lint and unit tests (if any) pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• All commits have been signed for DCO

[hidmic]

Awesome!

[hidmic]

LGTM