Added a Builder Implementation for StackedTile and allowing that implementation to be used in TopGameAreaRender and TopFrontGameAreaRender

[Chenjox]

When utilizing StackedTiles in a GameArea composed of Blocks, the TopDownGameAreaRenderer and the TopDownFrontGameAreaRenderer would complain about StackedTile s missing implementation of Tile#toBuilder(). This Pull Request adds that functionality, allowing StackedTile to render.

The only thing I did aside from supplying my builder, was to change the existing Tile#toBuilder() method signature from TileBuilder to Builder<Tile> allowing my StackedTileBuilder to implement that method.

If I missed anything I will gladly add it.

[adam-arold]

@Chenjox I just saw that this was still open. Did you take a look at the build failure?

[adam-arold]

I'm closing this as I didn't get a response for a very long time.

[adam-arold]

@Chenjox