Fix encoding for prefix and commonPrefixes

[pinzon]

This pr addresses issue #5228. Now that the list_objects_v2 response has the EncodingType attribute, Boto3 tries to decode the attributes Prefix and the CommonPrefixes like with the name of a Key Object.

Changes:

• Encoding of Prefix and CommonPrefixes if necessary.
• The added test groups the multiple reproducers provided in the issue.

[codecov-commenter]

Codecov Report

Merging #5239 (079eaa9) into master (6a1a8ee) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #5239   +/-   ##
=======================================
  Coverage   95.86%   95.86%           
=======================================
  Files         688      688           
  Lines       68240    68244    +4     
=======================================
+ Hits        65419    65423    +4     
  Misses       2821     2821           

Flag	Coverage Δ
servertests	36.39% <25.00%> (-0.01%)	⬇️
unittests	95.80% <100.00%> (+<0.01%)	⬆️

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

Impacted Files	Coverage Δ
moto/s3/responses.py	95.51% <100.00%> (+0.01%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 6a1a8ee...079eaa9. Read the comment docs.

[bblommers]

Nice one - thanks for fixing this @pinzon!

[github-actions]

This is now part of moto >= 3.1.14.dev15