JSSpecCompiler: Introduce Function and ExecutionContext classes

Currently, they are not extremely useful, but the plan is to store
all function-local state in JSSpecCompiler::Function and all
"translation unit" state in ExecutionContext.

Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/Function.cpp

@@ -0,0 +1,19 @@
+/*
+ * Copyright (c) 2023, Dan Klishch <danilklishch@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "Function.h"
+#include "AST/AST.h"
+
+namespace JSSpecCompiler {
+
+Function::Function(ExecutionContext* context, StringView name, Tree ast)
+    : m_context(context)
+    , m_name(name)
+    , m_ast(move(ast))
+{
+}
+
+}