Use MM's new UnitNameTracker for name collisions

[sixlettervariables]

This switches to using MegaMek's new UnitNameTracker to avoid name collisions for a campaign.

Depends on MegaMek/megamek#2632

[codecov]

Codecov Report

Merging #2445 (86abed2) into master (8404d38) will increase coverage by 0.02%.
The diff coverage is 17.24%.

@@             Coverage Diff              @@
##             master    #2445      +/-   ##
============================================
+ Coverage     10.32%   10.34%   +0.02%     
- Complexity     3406     3417      +11     
============================================
  Files           673      673              
  Lines         94656    94658       +2     
  Branches      15926    15926              
============================================
+ Hits           9771     9795      +24     
+ Misses        83511    83500      -11     
+ Partials       1374     1363      -11     

Impacted Files	Coverage Δ	Complexity Δ
MekHQ/src/mekhq/campaign/mission/BotForce.java	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
...ign/mission/atb/AtBScenarioModifierApplicator.java	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
MekHQ/src/mekhq/campaign/Campaign.java	11.33% <33.33%> (+0.13%)	94.00 <1.00> (+1.00)
MekHQ/src/mekhq/campaign/unit/Unit.java	20.38% <100.00%> (+0.05%)	207.00 <0.00> (ø)
MekHQ/src/mekhq/campaign/universe/Planet.java	26.30% <0.00%> (+0.22%)	25.00% <0.00%> (ø%)
MekHQ/src/mekhq/campaign/mission/AtBContract.java	19.22% <0.00%> (+0.23%)	65.00% <0.00%> (+2.00%)
...ekhq/campaign/universe/RandomFactionGenerator.java	60.16% <0.00%> (+1.65%)	64.00% <0.00%> (+2.00%)
...ekHQ/src/mekhq/campaign/market/ContractMarket.java	59.84% <0.00%> (+2.36%)	115.00% <0.00%> (+6.00%)

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