Improve vmdk extent descriptor parsing

[JSCU-CNI]

This PR improves the parsing of VMDK config strings, particularly extent descriptors. We introduced a new ExtentDescriptor dataclass to conveniently store all possible attributes of an extent. Fixes #45.

[codecov]

Codecov Report

Attention: Patch coverage is 70.45455% with 13 lines in your changes missing coverage. Please review.

Project coverage is 63.11%. Comparing base (98a9a66) to head (80afc8e).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
dissect/hypervisor/disk/vmdk.py	70.45%	13 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #44      +/-   ##
==========================================
+ Coverage   61.62%   63.11%   +1.48%     
==========================================
  Files          27       27              
  Lines        2356     2375      +19     
==========================================
+ Hits         1452     1499      +47     
+ Misses        904      876      -28     

Flag	Coverage Δ
unittests	63.11% <70.45%> (+1.48%)	⬆️

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