refactor: small readability improvements for maximizer constraints

[midgleyc]

1. Rename checkEffectConstraints to what it does
2. Make checkConstraints return an enum describing what each number means

[codecov]

Codecov Report

Merging #1506 (0c7a3e6) into main (e4b62b2) will increase coverage by 0.02%.
The diff coverage is 64.70%.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1506      +/-   ##
============================================
+ Coverage     34.73%   34.76%   +0.02%     
- Complexity    17378    17382       +4     
============================================
  Files          1062     1062              
  Lines        163275   163278       +3     
  Branches      34927    34926       -1     
============================================
+ Hits          56712    56760      +48     
+ Misses        97030    96984      -46     
- Partials       9533     9534       +1     

Impacted Files	Coverage Δ
...et/sourceforge/kolmafia/moods/ManaBurnManager.java	1.48% <0.00%> (ø)
...rc/net/sourceforge/kolmafia/moods/MoodTrigger.java	55.55% <0.00%> (ø)
.../sourceforge/kolmafia/webui/CharPaneDecorator.java	26.33% <0.00%> (ø)
.../net/sourceforge/kolmafia/maximizer/Evaluator.java	62.61% <75.00%> (+0.10%)	⬆️
...sourceforge/kolmafia/session/InventoryManager.java	34.18% <75.00%> (+0.38%)	⬆️
src/net/sourceforge/kolmafia/KoLmafia.java	36.78% <100.00%> (+4.42%)	⬆️
.../net/sourceforge/kolmafia/maximizer/Maximizer.java	36.66% <100.00%> (ø)
...et/sourceforge/kolmafia/swingui/CalendarFrame.java	67.46% <0.00%> (-2.39%)	⬇️
...rceforge/kolmafia/persistence/HolidayDatabase.java	69.76% <0.00%> (-0.52%)	⬇️
... and 4 more

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