Changes to toolchain-related files and PACKAGE files are not picked up by the change detector

[michaeleisel]

Suppose I have a PACKAGE file that includes:

...
configurations = {
    "clang-debug": [
        "root//build/platforms:cxx-20",
        "root//build/platforms:clang-18",
        "root//build/platforms:debug",
    ],
...

and I change the cxx-20 to cxx-23. If I run supertd btd --cells cells.json --changes changes.txt --base base.jsonl --universe root//... --track-prelude-rule-changes --json-lines root//..., it doesn't show any targets as being changed in that directory, even though many were affected.

Also, if I make a change to a file involved in the toolchain, e.g. some cxx_toolchain.bzl file, it should show all the C++ targets as being affected, but instead it shows nothing.