Fix: Tank armor and invalid builds

[Scoppio]

Fixes issue MegamekLab #1674.

It makes sure the correct armor tech level is loaded when loading the tank or SV.
It also makes sure the correct tech level is persisted when saving the non-mek entity.

This also adds a list of reasons/justifications to why a canon unit build is invalid, and allows it to be loaded.
If the unit is changed in a way to make it lose its canon status (change the MUL to -1 or change the name to something that is not in the canon names list) it will stop saving the reasons list for the build fail.

Also adds a bulk file verification test for all units in MegaMek.

Fixes:

• SV and Tank patchwork (IS and Clan)
• SV and Tank high tech armor level and rating (IS and Clan)

Implements:

• Build specific tag for canon units with the reason for failing build (only for BLK files)
• The invalid build reason tags are lost when making custom units derived from canon units (only for BLK files)

Example of use in a BLK file:

<invalidSourceBuildReasons>
UNIT_OLDER_THAN_EQUIPMENT_INTRO_YEAR
</invalidSourceBuildReasons>

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 28.98%. Comparing base (957e8e5) to head (243b211).
Report is 9 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #6343   +/-   ##
=========================================
  Coverage     28.97%   28.98%           
- Complexity    14087    14089    +2     
=========================================
  Files          2673     2674    +1     
  Lines        269472   269480    +8     
  Branches      47967    47968    +1     
=========================================
+ Hits          78087    78103   +16     
+ Misses       187402   187397    -5     
+ Partials       3983     3980    -3     

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[Sleet01]

Looks great; this will be a godsend.