Update AlisesFile and AliasDefinitionsFile to stop extending File, and
instead use composition as its much cleaner.
Moved AliasesFile and AliasDefinitionsFile into their own packages in
preparation for changes to split the code out into a number of classes
that each have a 'single responsibility'.
Created data classes that contain only the data, and not the behavior,
in preparation for creating Reader and Writer classes that operate
directly on the data objects.
Created Reader classes that allow the Data classes to be updated based
on the file contents.
Created Writer classes that allow the Data classes to be serialized to
file.
Moved the functionality that was previously in AliasUtility into
AliasesFile, now that AliasesFile is much easier to comprehend.