Add convenience methods to FileName attribute

[Schamper]

Closes #47.

[codecov]

Codecov Report

❌ Patch coverage is 33.33333% with 16 lines in your changes missing coverage. Please review.
✅ Project coverage is 87.42%. Comparing base (cce5fd7) to head (66cc4c3).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
dissect/ntfs/attr.py	36.36%	14 Missing ⚠️
dissect/ntfs/mft.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #48      +/-   ##
==========================================
- Coverage   88.41%   87.42%   -0.99%     
==========================================
  Files          11       11              
  Lines        1226     1249      +23     
==========================================
+ Hits         1084     1092       +8     
- Misses        142      157      +15     

Flag	Coverage Δ
unittests	87.42% <33.33%> (-0.99%)	⬇️

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[Miauwkeru]

With file_attribute above in mind, wouldn't using the resulting value and checking whether the attribute DIRECTORY exists be more logical? With the question: What if FILE_ATTRIBUTE.DIRECTORY is set and not FILE_NAME_INDEX_PRESENT?

[Schamper]

This check is faster.

And FILE_ATTRIBUTE.DIRECTORY is not a legal flag in this structure.