🐛 Handled BOM character for Unicode encoded file uploads

[vershwal]

#16917

For details of how I debugged this issue, see this comment: #16917 (comment)

After this PR, I was able to upload the file provided in the issue and I have also tested it by uploading other files of ascii and utf-8 encoding.

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.02 🎉

Comparison is base (498e166) 71.59% compared to head (9ab6003) 71.62%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #17104      +/-   ##
==========================================
+ Coverage   71.59%   71.62%   +0.02%     
==========================================
  Files        1817     1817              
  Lines      115364   115370       +6     
  Branches    17143    17147       +4     
==========================================
+ Hits        82600    82638      +38     
+ Misses      31638    31610      -28     
+ Partials     1126     1122       -4     

Flag	Coverage Δ
e2e-tests	66.51% <ø> (+0.02%)	⬆️
unit-tests	63.47% <100.00%> (+0.02%)	⬆️

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

Impacted Files	Coverage Δ
ghost/members-csv/lib/parse.js	81.81% <100.00%> (ø)

... and 15 files with indirect coverage changes

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