[WIP] add zipfile collection support

[ctb]

Note: Merge into #1420

This merges the zipfile collection stuff in #1349 with the much-simplified database loading in #1406 and signature selection in #1420.

Checklist

• Is it mergeable?
• make test Did it pass the tests?
• make coverage Is the new code covered?
• Did it change the command-line interface? Only additions are allowed
  without a major version increment. Changing file formats also requires a
  major version number increment.
• Was a spellchecker run on the source code and documentation after
  changes were made?
• Please note your ORCID in the comments. If you don't have one, you can register for one here.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (refactor/siglist_loading@6d8663e). Click here to learn what that means.
The diff coverage is n/a.

@@                     Coverage Diff                     @@
##             refactor/siglist_loading    #1429   +/-   ##
===========================================================
  Coverage                            ?   67.37%           
===========================================================
  Files                               ?       27           
  Lines                               ?     3614           
  Branches                            ?        0           
===========================================================
  Hits                                ?     2435           
  Misses                              ?     1179           
  Partials                            ?        0           

Flag	Coverage Δ
rust	67.37% <0.00%> (?)

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[ctb]

closing now that #1420 and #1406 are merged => #1349.