Gym basics

TODO: in this section, discuss some of the basic objects in the gym ecosystem.

From the invrs_gym package:

• Component: represents the physical component to be optimized. Has init and response methods. For some components, the response method has optional arguments that enable calculation of fields or other quantities for visualization purposes.

• Challenge: represents the challenge. Has a Component as an attribute, a loss function, an eval_metric function which scores a solution (higher is better), and metrics which returns additional relevant quantities.

From the totypes package:

• Density2DArray: array with metadata, used to parameterized layers that can be patterned. Includes metadata that can communicate desired minimum length scales to an optimizer.

• BoundedArray: array with optional upper and lower bounds, used to parameterize thicknesses.