Align dispenser boat placement on ice with vanilla waterlogged behavior

[brandonhenness]

This pull request updates the existing dispensersPlaceBoatsOnIce rule so that dispenser boat placement on ice follows the same logic that vanilla applies when placing boats into water or waterlogged blocks.

Summary of changes

• Ice directly in front of a dispenser now applies the same upward placement offset that vanilla uses for waterlogged blocks
• When air is in front and ice is one block below, boats are placed at the normal height, matching vanilla behavior for air-over-water
• Extends vanilla BoatDispenserBehavior logic to ice while preserving all original placement conditions and offsets

Linked issue

Fixes #358

Testing

I tested this feature extensively to ensure full parity with vanilla behavior:

• Ice directly in front
• Ice one block below front
• Dispensers facing all directions
• Dispensers above and below ice
• Waterlogged blocks with:
  • solid blocks in front
  • slabs in front
  • slabs above
  • full blocks above
• Mixed configurations of ice, air, and blocks
• All combinations verified to match vanilla boat placement logic where applicable

Screenshot of the tests is attached below.