tests/micropython: Add test for micropython.kbd_intr().

tests/micropython/kbd_intr.py

+# test the micropython.kbd_intr() function
+
+import micropython
+
+try:
+    micropython.kbd_intr
+except AttributeError:
+    print('SKIP')
+    import sys
+    sys.exit()
+
+# just check we can actually call it
+micropython.kbd_intr(3)