Initial support for signed URLs

[oittaa]

No description provided.

[codecov-commenter]

Codecov Report

Merging #129 (67a9ee5) into main (1956d44) will increase coverage by 0.08%.
The diff coverage is 77.77%.

@@            Coverage Diff             @@
##             main     #129      +/-   ##
==========================================
+ Coverage   87.42%   87.51%   +0.08%     
==========================================
  Files           7        7              
  Lines         851      857       +6     
  Branches      117      116       -1     
==========================================
+ Hits          744      750       +6     
- Misses         80       81       +1     
+ Partials       27       26       -1     

Flag	Coverage Δ
unittests	87.51% <77.77%> (+0.08%)	⬆️

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Impacted Files	Coverage Δ
gcp_storage_emulator/handlers/objects.py	88.02% <75.00%> (-0.38%)	⬇️
gcp_storage_emulator/server.py	85.87% <100.00%> (+0.65%)	⬆️

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[oittaa]

Now two of the most common cases should be supported: downloading and uploading with the signed URLs. #128