Added derivation of TDF base class, for AVR8 targets.

Includes initialisation and validation code.

build/scripts/TargetDescriptionFiles/PhysicalInterface.php

@@ -0,0 +1,8 @@
+<?php
+namespace Bloom\BuildScripts\TargetDescriptionFiles;
+
+class PhysicalInterface
+{
+    public ?string $name = null;
+    public ?string $type = null;
+}