[improvement] improve map generation

[clay-arras]

description: current map generation sucks.

criteria:

• map generation needs to generate realistic obstacles.
• map generation needs to have one large connected "air" space. (i.e., the robot must be able to visit every single grass tile on the map).
• there must be more grass tiles than wall tiles.

notes:

• current maze generation is in util/maze_generators.py, with a basic DFS maze generator. the initial map is all walls; the DFS carves paths, making visited nodes air.
• the robot and target are randomly placed, and then another DFS is used to make sure there's a valid path between the two.

ideas:

• make map generation use curved walls instead of blocks so the robot doesn't get stuck.
• create a validation script that ensures the outputted map follows the above criteria.

[clay-arras]

Rohan