vlib: add a wasm module, implementing a pure V webassembly seralisation library (#17909)

examples/wasm_codegen/add.v

@@ -0,0 +1,13 @@
+import wasm
+
+fn main() {
+	mut m := wasm.Module{}
+	mut func := m.new_function('add', [.i32_t, .i32_t], [.i32_t])
+	{
+		func.local_get(0)
+		func.local_get(1)
+		func.add(.i32_t)
+	}
+	m.commit(func, true) // `export: true`
+	print(m.compile().bytestr())
+}