Fix reality anchor light passability

[SirEdvin]

Summary

• make configured reality anchors use maximum light opacity when light passability is disabled
• add a world-level GameTest with skylight and glowstone above an enclosed anchor
• verify both blocked and passable configurations against the block below

Testing

• timeout --foreground 20m xvfb-run -a ./gradlew gameTest --no-daemon -PminimalTestEnvironment
• timeout --foreground 10m ./gradlew build --no-daemon

Closes #54

[SirEdvin]

As I expected, this shit is not work this way :)