Move the extension test to examples

pytest.ini

@@ -4,7 +4,7 @@ addopts = --doctest-modules
 # Ignore broken files in blackbox test directories
 norecursedirs = .* docs completion refactor namespace_package
     scripts extensions speed static_analysis not_in_sys_path
-    sample_venvs init_extension_module jedi/third_party
+    sample_venvs jedi/third_party
 
 # Activate `clean_jedi_cache` fixture for all tests.  This should be
 # fine as long as we are using `clean_jedi_cache` as a session scoped