pyright type checking: Initial setup

* Update imports to use fully qualified module name
* Add `typecheck` target to Makefile
* Add type annotations to appease pyright
* Switch from importlib_resources backport library to stdlib
  import.resources

etc/api/type-cli.yaml

@@ -5,7 +5,7 @@ mkdocs:
   # if docs_dir changes, remember to update the sources as well.
   docs_dir: docs
 mako:
-  post_processor_module: cli
+  post_processor_module: "lib.cli"
 make:
   id: cli
   target_name: CLIs