Enable exclusion of analysis by filename (rather than only package)

[PurelyApplied]

Currently, configuration permits exclusion of functions from levee analysis (but not upstream analyzers) via the Exclude: clause. However, a consumer may wish to exclude analysis based on filename. In particular, consumers that use a vendor/ directory may wish to exclude analysis and possible findings from packages outside their control. These vendor/ packages do not contain vendor in the package's path, so exclusion would currently need to be done on a per-package basis. While functional, it presents a potential pain point for consumers.