[decomp] Fix flipped byte addressing add and support some VU ops in the parser (#631)

* fix flipped order

* format

* parser hack

* actually flip

test/decompiler/test_InstructionParser.cpp

@@ -39,4 +39,13 @@ TEST(DecompilerInstructionParser, ProgramLabels) {
       "  jr ra\n";
   auto result = parser.parse_program(program);
   EXPECT_EQ(result.print(), program);
+}
+
+TEST(DecompilerInstructionParser, VU) {
+  InstructionParser parser;
+  std::string program =
+      "  vmove.xy vf1, vf2\n"
+      "  vsub.yw vf1, vf2, vf25\n";
+  auto result = parser.parse_program(program);
+  EXPECT_EQ(result.print(), program);
 }