GrinnsRPG - Structure Management and Boss Requirements

- Introduced a new "Policy" system for structure management, essentially allowing structures to be generated according to progression based on distance from 0,0 (world center). This new system has three new policies that are now implemented; NATURAL, PREFERRED, and GUARANTEED.

NATURAL - Allowing structures to be naturally generated after a configured minimum distance from world center
PREFERRED - Follows progression placement preferences while retaining natural generation behavior
GUARANTEED - Plans out and modifies world generation to have a much higher success rate of a structure generating within it's configured distance percentages (minimum, ideal, and maximum)

Any structures not listed within the config follow vanilla generation (or if you have TerraBlender, it follows the generation method that mod implements).