Overwrite FileResponse Content-Type with application/octet-stream for all files in /store

[AliveDevil]

Fixes #1059

[AliveDevil]

Should these be squashed? @aparcar

[codecov]

Codecov Report

Attention: Patch coverage is 73.33333% with 4 lines in your changes missing coverage. Please review.

Project coverage is 90.47%. Comparing base (5e65dec) to head (122d701).
Report is 141 commits behind head on main.

Files with missing lines	Patch %	Lines
asu/fastapi/StaticFiles.py	69.23%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1064      +/-   ##
==========================================
+ Coverage   80.75%   90.47%   +9.71%     
==========================================
  Files          15       15              
  Lines         977     1123     +146     
==========================================
+ Hits          789     1016     +227     
+ Misses        188      107      -81     

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[AliveDevil]

This is ugly.

But conftest.py overwrites settings.public_path, unfortunately the main.py/app has already been constructed, with the previous old public_path.
Thus the conftest.py app()-setting of public_path to a temp-path doesn't work here.