Add tally missing trustees feature

[leio10]

This PR adds the ability to report missing trustees during the tally process, to trigger the compensation of missing trustees to complete the process.

[codecov-commenter]

Codecov Report

Merging #202 (45c2bf9) into develop (e22d715) will increase coverage by 0.16%. The diff coverage is 77.33%.

@@             Coverage Diff             @@
##           develop     #202      +/-   ##
===========================================
+ Coverage    69.93%   70.09%   +0.16%     
===========================================
  Files           92       95       +3     
  Lines         1520     1585      +65     
===========================================
+ Hits          1063     1111      +48     
- Misses         457      474      +17     

Impacted Files	Coverage Δ
...er/app/controllers/sandbox/elections_controller.rb	0.00% <0.00%> (ø)
...app/services/voting_scheme/dummy/bulletin_board.rb	80.95% <61.29%> (-12.50%)	:arrow_down:
.../server/app/commands/concerns/log_entry_command.rb	94.82% <66.66%> (-1.61%)	:arrow_down:
...oard/server/app/commands/report_missing_trustee.rb	100.00% <100.00%> (ø)
...aphql/mutations/report_missing_trustee_mutation.rb	100.00% <100.00%> (ø)
...in_board/server/app/graphql/types/mutation_type.rb	100.00% <100.00%> (ø)
...oard/server/app/jobs/report_missing_trustee_job.rb	100.00% <100.00%> (ø)
...ices/voting_scheme/electionguard/bulletin_board.rb	81.81% <100.00%> (ø)
... and 1 more

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