Enhanced app_midi_simple to support file based commands and readiness for Rx testing

tests/midi_test_helpers.py

@@ -0,0 +1,24 @@
+# Copyright 2024 XMOS LIMITED.
+# This Software is subject to the terms of the XMOS Public Licence: Version 1.
+
+class Midi_expect:
+    def __init(self):
+        pass
+
+    def expect(self, commands):
+        expected = ""
+        for command in commands:
+            while len(command) < 3:
+                command.append(0)
+            expected += "uart_tx_checker: " + " ".join([f"0x{byte:02x}" for byte in command]) + "\n"
+
+        return expected
+
+
+def create_midi_tx_file(commands):
+    with open("midi_tx_cmds.txt", "wt") as mt:
+        for command in commands:
+            while len(command) < 3:
+                command.append(0)
+            text = " ".join([str(byte) for byte in command]) + "\n"
+            mt.write(text)