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

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

codex-rs/execpolicy/src/arg_resolver.rs

@@ -30,7 +30,7 @@ pub fn resolve_observed_args_with_patterns(
     // `suffix_patterns` and use that to determine how many args are left to
     // be matched by `vararg_pattern` (which could be zero).
     //
-    // After assocating positional args with `vararg_pattern`, we match the
+    // After associating positional args with `vararg_pattern`, we match the
     // `suffix_patterns` with the remaining args.
     let ParitionedArgs {
         num_prefix_args,