[EXP] add support for rapid signature selection from Zipfile collections by md5 picklists

[ctb]

NOTE: PR into #1588

This PR is an experimental PR that does some terrible things to ZipfileLinearIndex in order to support rapid picklist extraction. In exchange for those terrible things, it enables cool stuff like rapid extraction of signatures from large collections per #1365.

a demonstration

Below, we run a prefetch of a signature against 48,000 signatures in a zipfile collection, which yields 13 matches (for this query). We then use the picklist functionality in sourmash sig extract with the match_md5 column from the prefetch results to extract just the relevant signatures.

With this PR, the sourmash sig extract takes about 2 seconds. With #1588 (which supports picklists but not any special zipfile interaction), it takes a few minutes.

% sourmash prefetch podar-ref/63.fa.sig gtdb-r202.genomic-reps.k31.zip -o 63.prefetch.csv
...
(takes a few minutes, yields a prefetch.csv with 13 results)
...
% sourmash sig extract --picklist 63.prefetch.csv:match_md5:md5prefix8 \
         gtdb-r202.genomic-reps.k31.zip -o /tmp/abc.zip
picking column 'match_md5' of type 'md5prefix8' from '63.prefetch.csv'
loaded 13 distinct values into picklist.
loaded 13 sigs from 'gtdb-r202.genomic-reps.k31.zip'
loaded 13 total that matched ksize & molecule type
extracted 13 signatures from 1 file(s)
for given picklist, found 13 matches of 13 total

[codecov]

Codecov Report

Merging #1589 (e205e64) into add/picklist_selectors (a88b66d) will decrease coverage by 0.28%.
The diff coverage is 37.14%.

@@                    Coverage Diff                     @@
##           add/picklist_selectors    #1589      +/-   ##
==========================================================
- Coverage                   89.05%   88.77%   -0.29%     
==========================================================
  Files                          76       76              
  Lines                        6736     6763      +27     
  Branches                     1209     1218       +9     
==========================================================
+ Hits                         5999     6004       +5     
- Misses                        520      540      +20     
- Partials                      217      219       +2     

Flag	Coverage Δ
python	88.77% <37.14%> (-0.29%)	⬇️

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Impacted Files	Coverage Δ
src/sourmash/index.py	94.11% <37.14%> (-4.92%)	⬇️

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[ctb]

Closing in favor of #1590, which is more general.