Show refitting techs and fix refit countdown

[WeaverThree]

Fixes an error in calcluating the number of days left on a refit caused by not discounting time spent by a tech assigned to both do the refit and maintain the mech being refit.

Also marks techs that are doing refits in the personnel column.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 10.52%. Comparing base (dfef5ae) to head (907de4f).
Report is 16 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #5180   +/-   ##
=========================================
  Coverage     10.51%   10.52%           
- Complexity     6040     6044    +4     
=========================================
  Files           957      957           
  Lines        134513   134523   +10     
  Branches      19544    19545    +1     
=========================================
+ Hits          14141    14153   +12     
- Misses       119018   119021    +3     
+ Partials       1354     1349    -5     

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