Investigate Bad TilemapCollider Performance in Extreme Cases

Summary

Tilemap Collider generation is too slow in "extreme" cases, causing micro-freezes during editing and at runtime when editing tilemaps.

How to reproduce

• Create a simple tileset with two tiles - one fully passable and one fully blocking.
• Create a new tilemap that is at least 32x32.
• Edit the tilemap to create a checkerboard pattern of blocking and passable tiles.
• Profile and check performance while editing.

Reported on the chat by user TBDesignes.