Sprite Packer mode for the current project.
| Disabled | Doesn't pack sprites. |
| BuildTimeOnlyAtlas | Pack all the SpriteAtlas when building player/bundles. |
| AlwaysOnAtlas | Always pack all the SpriteAtlas. |
| SpriteAtlasV2 | If enabled, will automatically migrate all *.spriteatlas assets to *.spriteatlasv2 assets. Old *.spriteatlas assets will be removed. |