Allow Blocks to specify their max stack size

src/block/BaseBanner.php

@@ -75,6 +75,10 @@ abstract class BaseBanner extends Transparent{
 		return false;
 	}
 
+	public function getMaxStackSize() : int{
+		return 16;
+	}
+
 	/**
 	 * @return BannerPatternLayer[]
 	 * @phpstan-return list<BannerPatternLayer>

src/block/BaseSign.php

@@ -68,6 +68,10 @@ abstract class BaseSign extends Transparent{
 		return false;
 	}
 
+	public function getMaxStackSize() : int{
+		return 16;
+	}
+
 	/**
 	 * @return AxisAlignedBB[]
 	 */

src/block/Block.php

@@ -439,6 +439,13 @@ class Block{
 		return 0;
 	}
 
+	/**
+	 * Returns the maximum number of this block that can fit into a single item stack.
+	 */
+	public function getMaxStackSize() : int{
+		return 64;
+	}
+
 	/**
 	 * Returns the chance that the block will catch fire from nearby fire sources. Higher values lead to faster catching
 	 * fire.