fix(HeadFile): fix dis reversal, expand tests

[wpbonelli]

Fix the write logic for head file reversal to properly write each layer. Add a test for each discretization type. Fix in-place reverse by writing to a temp file first then renaming. Improve docstrings.

@cneyens could you check if this resolves #2246 on your end?

[codecov]

Codecov Report

Attention: Patch coverage is 98.21429% with 1 line in your changes missing coverage. Please review.

Project coverage is 75.7%. Comparing base (9dd66c7) to head (4341c30).

Additional details and impacted files

@@            Coverage Diff            @@
##           develop   #2247     +/-   ##
=========================================
+ Coverage     73.6%   75.7%   +2.0%     
=========================================
  Files          294     294             
  Lines        59029   58909    -120     
=========================================
+ Hits         43476   44624   +1148     
+ Misses       15553   14285   -1268     

Files	Coverage Δ
flopy/utils/binaryfile.py	86.4% <98.2%> (+4.3%)	⬆️

... and 142 files with indirect coverage changes

[wpbonelli]

I did some testing on example models, this seems to work OK for structured and unstructured grids. Feel free to reopen if you still see issues @cneyens.