Add codespell support (config, workflow to detect/not fix) and make it fix some typos (#903)

More about codespell: https://github.com/codespell-project/codespell .

I personally introduced it to dozens if not hundreds of projects already
and so far only positive feedback.

CI workflow has 'permissions' set only to 'read' so also should be safe.

Let me know if just want to take typo fixes in and get rid of the CI

---------

Signed-off-by: Yaroslav O. Halchenko <debian@onerussian.com>

codex-rs/execpolicy/src/default.policy

@@ -136,7 +136,7 @@ define_program(
         ["--glob", "src"],
     ],
     # TODO(mbolin): Perhaps we need a way to indicate that we expect `rg` to be
-    # bundled with the host environment and we should be using that verison.
+    # bundled with the host environment and we should be using that version.
     system_path=[],
 )