Add function to validate byte code against source code

test/contracts/validation_test1.aes

@@ -0,0 +1,4 @@
+contract ValidationTest =
+  payable entrypoint attr_fail() = ()
+  entrypoint type_fail(x : int) = x
+  entrypoint code_fail(x) = x + 1

test/contracts/validation_test2.aes

@@ -0,0 +1,4 @@
+contract ValidationTest =
+  entrypoint attr_fail() = ()
+  entrypoint type_fail(x) = x
+  entrypoint code_fail(x) = x - 1

test/contracts/validation_test3.aes

@@ -0,0 +1,4 @@
+payable contract ValidationTest =
+  payable entrypoint attr_fail() = ()
+  entrypoint type_fail(x : int) = x
+  entrypoint code_fail(x) = x + 1