Fugue support for extra helper functions from core

[fdosani]

Currently there are some helper functions as part of the core Pandas code which I think are generally very helpful. We need to spend some time exploring those and seeing which ones can be mirrored/included via the Fugue implementation.

This is just a list of most of the functions. Not all will make sense to move over. But we should investigate which ones make sense to:

• [x] df1_unq_columns (#217)
• [x] df2_unq_columns (#217)
• [x] intersect_columns (#217)
• [x] all_columns_match (#219)
• [x] all_rows_overlap (#244)
• [x] count_matching_rows (#294)
• [ ] intersect_rows_match
• [x] matches (is_match)
• [ ] subset
• [ ] sample_mismatch
• [ ] all_mismatch
• [ ] columns_equal
• [ ] compare_string_and_date_columns

Need to look into a bit more. low prio for now.

• [ ] get_merged_columns
• [ ] temp_column_name
• [ ] calculate_max_diff
• [ ] generate_id_within_group

[fdosani]

@goodwanghan @kvnkho FYI, no pressure to contribute, but something in our backlog I'm thinking to ensure full parity in terms of function etc.

[goodwanghan]

Sounds good, let's chat about it