Optimize mapExceptionM

Instead of `mapExceptionM` needing to catch and transform exceptions immediately, we could just track a `AnyException SomeException -> e` function that would defer the transformation to when the exception is actually caught.
```hs
mapExceptionM f (UnsafeIOE (io, convertE)) = UnsafeIOE (io, f . convertE)

catchAnyM (UnsafeIOE (m, convertE)) f =
withRunAsIOE $ \run ->
UnsafeIOE (m `GHC.catch` (unIOE . run . f . convertE), castAnyException)
```

Start by locating mapExceptionM, catchAnyM, and UnsafeIOE in the Haskell sources, then read how exceptions are currently converted and caught. Verify the proposed deferred transformation preserves the existing exception behavior, and add or update tests for both mapping and catching before considering the refactor complete.

Written by the indexing model from the issue text.