Implement stub tests and a first iteration of loading them from some random place

test/completion/stubs.py

@@ -0,0 +1,11 @@
+from stub_folder import with_stub, stub_only
+
+#? int()
+stub_only.in_stub_only
+
+#? str()
+with_stub.in_with_stub_both
+#? int()
+with_stub.in_with_stub_python
+#? float()
+with_stub.in_with_stub_stub