executors: fully type every single executor

[quantum5]

No description provided.

[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%)	⬆️
dmoj/executors/JAVA11.py	100.00% <ø> (+11.11%)	⬆️
dmoj/executors/JAVA15.py	100.00% <ø> (+11.11%)	⬆️
dmoj/executors/JAVA17.py	100.00% <ø> (ø)
dmoj/executors/JAVA9.py	100.00% <ø> (+11.11%)	⬆️
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%)	⬆️
dmoj/executors/RUBY2.py	84.78% <69.56%> (+3.83%)	⬆️
... and 48 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 73a6738...2029915. Read the comment docs.

[kiritofeng]

Superseded by #1147.