Convert stackMetadata to an extension property

It feels much more like a property than a function.

Signed-off-by: Graham <gpe@openrs2.dev>

asm/src/main/java/dev/openrs2/asm/InsnListUtils.kt

@@ -14,7 +14,7 @@ fun getExpression(
     var height = 0
     var insn: AbstractInsnNode? = last
     do {
-        val (pops, pushes) = insn!!.stackMetadata()
+        val (pops, pushes) = insn!!.stackMetadata
         if (insn !== last) {
             expr.add(insn)
             height -= pushes

asm/src/main/java/dev/openrs2/asm/StackMetadata.kt

@@ -181,7 +181,8 @@ private val SIMPLE_OPCODES = mapOf(
     Opcodes.IFNONNULL to POP1
 )
 
-fun AbstractInsnNode.stackMetadata(): StackMetadata = when (this) {
+val AbstractInsnNode.stackMetadata
+    get() = when (this) {
         is LdcInsnNode -> if (cst is Double || cst is Long) {
             PUSH2
         } else {

deob/src/main/java/dev/openrs2/deob/transform/ConstantArgTransformer.kt

@@ -262,7 +262,7 @@ class ConstantArgTransformer : Transformer() {
             } else if (!insn.pure) {
                 // can't replace instructions with a side effect
                 continue
-            } else if (insn.stackMetadata().pushes != 1) {
+            } else if (insn.stackMetadata.pushes != 1) {
                 // can't replace instructions pushing more than one result
                 continue
             }