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

examples/wasm_codegen/factorial.v

@@ -0,0 +1,33 @@
+import wasm
+
+fn main() {
+	mut m := wasm.Module{}
+	mut fac := m.new_function('fac', [.i64_t], [.i64_t])
+	{
+		fac.local_get(0)
+		fac.eqz(.i64_t)
+		fac.c_if([], [.i64_t])
+		{
+			fac.i64_const(1)
+		}
+		fac.c_else()
+		{
+			{
+				fac.local_get(0)
+			}
+			{
+				fac.local_get(0)
+				fac.i64_const(1)
+				fac.sub(.i64_t)
+				fac.call('fac')
+			}
+			fac.mul(.i64_t)
+		}
+		fac.c_end_if()
+	}
+	m.commit(fac, true)
+	print(m.compile().bytestr())
+
+	// v run factorial.v > a.wasm
+	// wasmer a.wasm -i fac 5
+}