MetaFileForPackage returns the expected name of the meta-data file for the package whose import path is 'importPath' in cases where we're using meta-data generated by the cover tool, as opposed to a meta-data file created at runtime.

CoverFixupConfig contains annotations/notes generated by the cmd/cover tool (during instrumentation) to be passed on to the compiler when the instrumented code is compiled.

CoverPkgConfig is a bundle of information passed from the Go command to the cover command during "go build -cover" runs.