Fixed #29942 -- Restored source file linking in docs by using the Sphinx linkcode ext.

Co-authored-by: David Smith <smithdc@gmail.com>
Co-authored-by: Natalia <124304+nessita@users.noreply.github.com>

tests/sphinx/testdata/package/module.py

@@ -0,0 +1,25 @@
+"""
+Example docstring
+"""
+
+from django.utils.functional import cached_property
+from tests.sphinx.testdata.package.wildcard_module import *  # noqa
+
+from . import other_module  # noqa
+from .other_module import MyOtherClass  # noqa
+
+
+class MyClass(object):
+    def __init__(self):
+        pass
+
+    def my_method(self):
+        pass
+
+    @cached_property
+    def my_cached_property(self):
+        pass
+
+
+def my_function(self):
+    pass