Bazel-diff does not calculate source file hashes for Bazel module repositories (Bazel 8 and later) #288
Description
At the moment bazel-diff does not recognise external repositories directory format that was introduced in Bazel 7 and became default in Bazel 8, which in turn leads to bazel-diff not reporting changes in the affected targets (but reporting "File not found" warnings with --verbose flag).
We've discovered this problem after migrating our monorepo to Bazel module and switching from Bazel 7 to Bazel 8. Our monorepo consists of several Bazel modules, we used --fineGrainedHashExternalRepos flag to calculate hashes 'per module', but found out that bazel-diff behaviour with Bazel Module differs from Bazel Workspace.
I've attached minimal reproducer, it compares bazel-diff behaviour using latest official version and patched version from our fork.