Filter out infra units from hit point calculation

[ron-murhammer]

Infra units can participate in battles but they have 0 HP and are either captured/destroyed if no other units remain. Fix the HP calculation and display in BC.

Example of HoH where cannon are infra:

[DanVanAtta]

LGTM

[codecov-io]

Codecov Report

Merging #3364 into master will increase coverage by <.01%.
The diff coverage is 66.66%.

@@             Coverage Diff              @@
##             master    #3364      +/-   ##
============================================
+ Coverage     21.95%   21.95%   +<.01%     
- Complexity     5886     5887       +1     
============================================
  Files           832      832              
  Lines         71877    71878       +1     
  Branches      11588    11589       +1     
============================================
+ Hits          15778    15780       +2     
  Misses        54015    54015              
+ Partials       2084     2083       -1

Impacted Files	Coverage Δ	Complexity Δ
...es/strategy/triplea/delegate/BattleCalculator.java	52.01% <66.66%> (-0.1%)	78 <0> (ø)
.../src/main/java/games/strategy/net/nio/Decoder.java	72.82% <0%> (-1.09%)	24% <0%> (-1%)
.../strategy/triplea/odds/calculator/DummyPlayer.java	36.36% <0%> (+1.13%)	10% <0%> (+1%)	⬆️
...rategy/triplea/attachments/UnitTypeComparator.java	53.84% <0%> (+7.69%)	13% <0%> (+1%)	⬆️

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