Add test of upload of large file to new API

[jwodder]

Closes #411.

[codecov]

Codecov Report

Merging #415 (d6035d3) into master (cdba8e2) will increase coverage by 0.14%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #415      +/-   ##
==========================================
+ Coverage   81.94%   82.08%   +0.14%     
==========================================
  Files          53       53              
  Lines        5561     5572      +11     
==========================================
+ Hits         4557     4574      +17     
+ Misses       1004      998       -6     

Flag	Coverage Δ
unittests	82.08% <100.00%> (+0.14%)	⬆️

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Impacted Files	Coverage Δ
dandi/tests/test_dandiapi.py	100.00% <100.00%> (ø)
dandi/dandiapi.py	88.88% <0.00%> (+2.56%)	⬆️

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