impl(storage): add conformance test fixtures

[alvarowolfx]

Add GCS conformance tests files, rust structs to read such files and base unit tests to run such tests.

Towards #3645

[codecov]

Codecov Report

❌ Patch coverage is 87.50000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 94.72%. Comparing base (e0ab583) to head (3f7bc99).
⚠️ Report is 11 commits behind head on main.

Files with missing lines	Patch %	Lines
src/storage/src/storage/signed_url.rs	87.50%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4133   +/-   ##
=======================================
  Coverage   94.72%   94.72%           
=======================================
  Files         183      183           
  Lines        6915     6922    +7     
=======================================
+ Hits         6550     6557    +7     
  Misses        365      365           

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[alvarowolfx]

sent a commit addressing the points raised