CI: add type checking (#10997)

* Set up type checking with mypy.

* Make mypy pass.

* Use list() instead of sorted().

plugins/test/a_module.py

@@ -43,7 +43,7 @@ from ansible.plugins.loader import action_loader, module_loader
 try:
     from ansible.errors import AnsiblePluginRemovedError
 except ImportError:
-    AnsiblePluginRemovedError = Exception
+    AnsiblePluginRemovedError = Exception  # type: ignore
 
 
 def a_module(term):

plugins/test/fqdn_valid.py

@@ -65,6 +65,7 @@ _value:
 
 from ansible.errors import AnsibleError
 
+ANOTHER_LIBRARY_IMPORT_ERROR: ImportError | None
 try:
     from fqdn import FQDN
 except ImportError as imp_exc: