Remove generatorify.py

[jwodder]

• generator_from_callback() hasn't been used since we removed the Girder code. If we need something like it again, we can use callback_iter() from more-itertools.
• callback_from_generator() has never been used.

[codecov]

Codecov Report

Merging #850 (96e82eb) into master (ca8d8c5) will increase coverage by 1.00%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #850      +/-   ##
==========================================
+ Coverage   85.63%   86.64%   +1.00%     
==========================================
  Files          61       60       -1     
  Lines        6280     6193      -87     
==========================================
- Hits         5378     5366      -12     
+ Misses        902      827      -75     

Flag	Coverage Δ
unittests	86.64% <ø> (+1.00%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
dandi/download.py	82.44% <0.00%> (-0.54%)	⬇️
dandi/dandiapi.py	89.69% <0.00%> (-0.18%)	⬇️
dandi/_version.py	45.96% <0.00%> (+1.75%)	⬆️

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[lgtm-com]

This pull request fixes 1 alert when merging 96e82eb into ca8d8c5 - view on LGTM.com

fixed alerts:

• 1 for Except block handles 'BaseException'

[yarikoptic]

thanks, let's proceed!