gazelle_cabal fails to execute on cabal because of Paths_* files

[googleson78]

Describe the bug
gazelle_cabal fails to execute on https://github.com/haskell/cabal with the following error:

gazelle: cabalscan: MissingModuleFile {modulePath = "Paths_Cabal", cabalFile = "/home/googleson78/git/cabal/Cabal/Cabal.cabal", componentName = "Cabal"}
gazelle: exit status 1

I believe this is because Paths_Cabal doesn't have an associated file, as it is autogenerated. Other files like this should have the same issue, but Paths_* is encountered much more often in my experience.

To Reproduce

0. Clone https://github.com/googleson78/cabal
1. Checkout 3749f6089a015bf18d661f89efa6672613210455
2. nix-shell
3. bazel run //:gazelle

[kczulko]

Probably @facundominguez may know more about getting rid of Paths_* as he probably was running gazelle_cabal against cabal code. Essentially, I mean this context.

BTW: I was encountering the same behavior in case of bazelifiyng example-servant-elm

[facundominguez]

When building Cabal, I wrote a Paths_Cabal.hs module instead of having cabal generate it:
facundominguez/cabal@4e0ab0d#diff-0028f8835685d6b965059b98ee873c6fbf4f1466097c0c82da6504d564aaa37c

Maybe we should list this workaround in the readme of gazelle_cabal. It doesn't look like generating the file with with gazelle_cabal would be easy.