This test covers a few vision bugs:
1. VisibilityInStraightLineOfSight - test case checks the visibility
of objects in a straight line of sight parallel to the X or Y
coordinate lines:
https://github.com/diasurgical/DevilutionX/pull/7901
2. NoVisibilityThroughAdjacentTiles - test case checks that nothing is
visible through the diagonally adjacent tiles:
https://github.com/diasurgical/DevilutionX/pull/7920
3. VisibleObjects - generic test, which makes sure some objects are
visible, but some - are not.
Signed-off-by: Roman Penyaev <r.peniaev@gmail.com>