[lld-macho] Make ObjC category checker print the source file name of category (#80221)

When printing category conflicts in the ObjC category checker, also
print the source file name of the problematic categories. Currently we
only print the object file name. This change is mostly useful only for
thinLTO builds, where the object file name will be of form
999.arm64.lto.o and thus does not reveal any information about the
original source file.

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Co-authored-by: Alex Borcan <alexborcan@meta.com>