Fixing MHQ's Javadoc Build

[Windchild292]

This continues on from MegaMek/megamek#3445 and MegaMek/megameklab#1028 to fix the Javadoc build for MekHQ.

Akin to the previous two, there are still huge gaps in our Javadoc coverages, and tons of warnings.

This also changes a bunch of copyright headers relating to < and > emails in the copyrights, as it was far easier to just bulk rename than deal with it each of the hundred times it is used.

[codecov]

Codecov Report

Merging #3115 (01633b8) into master (119931a) will increase coverage by 0.01%.
The diff coverage is n/a.

❗ Current head 01633b8 differs from pull request most recent head ac6c4e1. Consider uploading reports for the commit ac6c4e1 to get more accurate results

@@             Coverage Diff              @@
##             master    #3115      +/-   ##
============================================
+ Coverage      9.93%    9.94%   +0.01%     
- Complexity     4057     4061       +4     
============================================
  Files           816      816              
  Lines        112195   112141      -54     
  Branches      17204    17196       -8     
============================================
+ Hits          11142    11153      +11     
+ Misses        99664    99602      -62     
+ Partials       1389     1386       -3     

Impacted Files	Coverage Δ
MekHQ/src/mekhq/Action.java	0.00% <ø> (ø)
MekHQ/src/mekhq/MekHQ.java	3.68% <ø> (+0.21%)	⬆️
MekHQ/src/mekhq/Utilities.java	3.22% <ø> (ø)
MekHQ/src/mekhq/campaign/Campaign.java	12.14% <ø> (+0.08%)	⬆️
MekHQ/src/mekhq/campaign/CampaignOptions.java	28.76% <ø> (ø)
MekHQ/src/mekhq/campaign/CurrentLocation.java	6.10% <ø> (ø)
MekHQ/src/mekhq/campaign/ExtraData.java	17.88% <ø> (ø)
MekHQ/src/mekhq/campaign/JumpPath.java	37.87% <ø> (ø)
MekHQ/src/mekhq/campaign/Kill.java	0.00% <ø> (ø)
...kHQ/src/mekhq/campaign/RandomSkillPreferences.java	12.29% <ø> (ø)
... and 206 more

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[SJuliez]

I will not look at this closely as it only concerns comments.