executors: fully type every single executor

[quantum5]

[codecov-commenter]

Codecov Report

Merging #951 (2029915) into master (73a6738) will increase coverage by 0.42%. The diff coverage is 94.19%.

@@            Coverage Diff             @@
##           master     #951      +/-   ##
==========================================
+ Coverage   86.46%   86.89%   +0.42%     
==========================================
  Files         138      138              
  Lines        4736     4905     +169     
==========================================
+ Hits         4095     4262     +167     
- Misses        641      643       +2     

Impacted Files	Coverage Δ
dmoj/executors/BASH.py	0.00% <0.00%> (ø)
dmoj/executors/JAVA10.py	100.00% <ø> (+11.11%)	:arrow_up:
dmoj/executors/JAVA11.py	100.00% <ø> (+11.11%)	:arrow_up:
dmoj/executors/JAVA15.py	100.00% <ø> (+11.11%)	:arrow_up:
dmoj/executors/JAVA17.py	100.00% <ø> (ø)
dmoj/executors/JAVA9.py	100.00% <ø> (+11.11%)	:arrow_up:
dmoj/executors/__init__.py	80.00% <0.00%> (ø)
dmoj/executors/script_executor.py	81.39% <33.33%> (ø)
dmoj/executors/OBJC.py	64.51% <66.66%> (+2.44%)	:arrow_up:
dmoj/executors/RUBY2.py	84.78% <69.56%> (+3.83%)	:arrow_up:
... and 48 more

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[kiritofeng]

Superseded by #1147.