Add: Imperial support to DivePlanner by passing the UnitSystem enum

[Rolf-Smit]

DivePlanner.addDive() is now aware of the UnitSystem. When UnitSystem.IMPERIAL is active, output depths are produced in feet and deco stops align to the 10 feet grid.

Required for: #49

[codecov-commenter]

Codecov Report

❌ Patch coverage is 91.66667% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 70.15%. Comparing base (e2052a2) to head (4aba438).

Files with missing lines	Patch %	Lines
...ech/app/abysner/domain/diveplanning/DivePlanner.kt	85.71%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #179      +/-   ##
==========================================
+ Coverage   70.10%   70.15%   +0.05%     
==========================================
  Files         145      145              
  Lines        7830     7847      +17     
  Branches      973      977       +4     
==========================================
+ Hits         5489     5505      +16     
- Misses       1850     1851       +1     
  Partials      491      491              

Flag	Coverage Δ
domain	78.14% <91.66%> (+0.17%)	⬆️
presentation	68.12% <ø> (ø)

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