Consider activation frame for stack height metering (#2)

* Charge a base cost for calling a function

* Added regression test for empty functions

* Satisfy clippy

tests/expectations/stack-height/simple.wat

@@ -5,7 +5,7 @@
     drop)
   (func (;1;) (type 0)
     global.get 0
-    i32.const 1
+    i32.const 3
     i32.add
     global.set 0
     global.get 0
@@ -16,7 +16,7 @@
     end
     call 0
     global.get 0
-    i32.const 1
+    i32.const 3
     i32.sub
     global.set 0)
   (global (;0;) (mut i32) (i32.const 0))