chore: Use FlexiblePathfinding / Remove Pathfinding

[skaldarnar]

• remove minion.work package
• remove grid package
• use org.terasology.module.behaviors as root namespace
• separate three packages actions, components, and systems
  • integrate nodes into actions as they are all behavior actions
  • rename system to systems to use consistent plural nouns
  • sort stray classes into respective package

• remove irrelevant or broken tests (i.e., all tests)

  src/main/java/
  └── org
          └── terasology
                  └── module
                          └── behaviors
                                  ├── actions
                                  ├── components
                                  └── systems

[jdrueckert]

FlexibleMovement as a replacement for PathFinding