LibWasm: Add basic support for module instantiation and execution stubs

This adds very basic support for module instantiation/allocation, as
well as a stub for an interpreter (and executions APIs).
The 'wasm' utility is further expanded to instantiate, and attempt
executing the first non-imported function in the module.
Note that as the execution is a stub, the expected result is a zero.
Regardless, this will allow future commits to implement the JS
WebAssembly API. :^)

Userland/Libraries/LibWasm/AbstractMachine/Interpreter.h

@@ -0,0 +1,17 @@
+/*
+ * Copyright (c) 2021, Ali Mohammad Pur <mpfard@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibWasm/AbstractMachine/Configuration.h>
+
+namespace Wasm {
+
+struct Interpreter {
+    void interpret(Configuration&);
+};
+
+}