Split Directory class

[benjaminLuoHC]

Define a base Directory class with get_files and filter, then make separate report classes that inherit from it

The current directory class is too big

Proposed usage:

from file_processing import MetadataReport, AnalyticsReport, SimilarityReport

MetadataReport('path/to/dir', **kwargs)
AnalyticsReport(...)
...

Proposed implementation

class Directory()
# init
# get_files
# filter

class MetadataReport(Directory)
# methods

Note: Tests would need minor refactoring