Unifying Deduplication API Modules

[praateekmahajan]

1. SemDedup currently outpus "ids to keep" while Fuzzy/Exact dedup outputs "ids to remove". Across our deduplication API we should make sure we have the same API
2. The deduplicator modules should have identify / remove and identify_and_remove ?
3. The __call__ should behave as identify_and_remove and advanced users who need to configure which dupe among dupes to keep (for exact / fuzzy) can call identify and remove separately?
4. Rename / remove current (Fuzzy)Duplicates in favor of a (Fuzzy)Deduplicator that has both methods

Architectural Design

1. Base class called BaseDeduplicator that has the abstract methods (feel free to suggest)
2. Exact and Fuzzy by default will keep randomly 1 of the documents in the "matched" groups, however users who have opinions on which dupe to keep, can break it into identify and dedup
3. Whether we output ids_to_keep or ids_to_remove is to be decided as we learn more on the performance implications in a dask merge