merge test-user-mode and test-baremetal into test-executables

Differentiate with --mode userland vs --mode baremetal.

The code was basically copied, now it's DRY.

test-executables-in-tree

@@ -0,0 +1,21 @@
+#!/usr/bin/env python3
+
+import lkmc.import_path
+
+test_user_mode = lkmc.import_path.import_path_relative_root('test-executables')
+
+class Main(test_user_mode.Main):
+    def __init__(self):
+        super().__init__(
+            description='''\
+https://github.com/cirosantilli/linux-kernel-module-cheat#userland-setup-getting-started-natively
+''',
+            defaults={
+                'emulators': ['native'],
+                'in_tree': True,
+                'tests': ['.'],
+            }
+        )
+
+if __name__ == '__main__':
+    Main().cli()