comparative analysis table fields not accessible via `fields` when filtering on a different dataset

[cmatKhan]

when querying harbison, it should be possible to add DTO fields via the fields argument to query.

In fact, need to think about how th ecomparative analysis eg perturbation_id is parsed out -- how to make it easy to say, give me all records in harbison. and then with result, group by hackett

[cmatKhan]

When filteirng on a field, i tshould at least return that field, eg when filtering on dto_empirical_pvalue, at least dto_empirical_pvalue should be returned

[cmatKhan]

What about filtering on harbison and hackett? eg I want to filter by dto_empirical_pvalue between harbison and hackett? is that best if done by specifying the dataset?

[rnajjj]

I've made these improvements, hoping they will be useful:

1. Added the _join_comparative_analyses function to _build_metadata_table to incorporate comparative datasets; _join_comparative_analyses queries the comparative dataset using SQL and then prepares for matching; _parse_composite_identifier: parses the ID from the comparative dataset for matching.
2. It worked successfully with Harbison, but failed with Hackett due to a case mismatch (uppercase H). Therefore, I added code to _join_comparative_analyses to try both uppercase and lowercase beginnings for the repo ID.
3. Added a query_dto function to specifically handle the intersection of specified binding and perturbation datasets.
4. I also found some inconsistencies between datasets: BrentLab/harbison_2004;harbison_2004;3
   BrentLab/rossi_2021/rossi_2021_af_combined
   Some use semicolons, others use slashes.

Some use uppercase, others use lowercase:
BrentLab/Hackett_2020;hackett_2020;34 BrentLab/harbison_2004;harbison_2004;3

Do we need to unify them? Or should we handle them separately with functions?
5. I failed to read the calling cards data; the program crashed several times, but I haven't found the reason yet, so I haven't continued with the analysis.

i forked Brentlab/dev and create pull request based on it.

show_new_functions.ipynb
virtual_db.py

[cmatKhan]

Closed in #73