fix for "malfunction when reading CZIs with empty attachment-directory via curl_http_inputstream"

[ptahmose]

Description

With a CZI containing an attachment-directory-segment with zero entries, we called into the stream-object reading 0 bytes. The curl_http_inputstream object happened to throw an exception for a read-request of zero length.
The expected behavior is now documented, the curl_http_inputstream object does now tolerate a read-request for zero bytes, and where this zero-bytes-read-request was issued, it is now checked if there actually is something to be read.

Fixes #98

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

locally (with a CZI-document triggering this malfunction)

Checklist:

• I followed the Contributing Guidelines.
• I did a self-review.
• I commented my code, particularly in hard-to-understand areas.
• I updated the documentation.
• I updated the version of libCZI following Versioning of libCZI depending on the type of change
  • Bug fix -> PATCH
  • New feature -> MINOR
  • Breaking change -> MAJOR
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.

[codecov]

Codecov Report

Attention: Patch coverage is 80.76923% with 5 lines in your changes are missing coverage. Please review.

Project coverage is 65.99%. Comparing base (9a7503b) to head (6f396da).
Report is 1 commits behind head on main.

Files	Patch %	Lines
Src/libCZI/CziParse.cpp	77.27%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #99      +/-   ##
==========================================
+ Coverage   65.97%   65.99%   +0.01%     
==========================================
  Files          85       85              
  Lines       10647    10653       +6     
==========================================
+ Hits         7024     7030       +6     
  Misses       3623     3623              

Flag	Coverage Δ
windows-latest	65.99% <80.76%> (+0.01%)	⬆️

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[m-aXimilian]

What I understood makes sense to me.

[soyers]

LGTM! Thanks for providing this fix so fast!

[DaveyJonesBitPail]

Looks good to me! Approved with a couple of questions and recommendations