Refactor all remaining engine endpoints to vertical slices

[ddaspit]

• closes Move remaining translation engine endpoints to vertical slices #912

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This change is 

[codecov-commenter]

Codecov Report

❌ Patch coverage is 86.35983% with 163 lines in your changes missing coverage. Please review.
✅ Project coverage is 66.18%. Comparing base (8fb56ee) to head (0926e8b).

Files with missing lines	Patch %	Lines
...on/Features/Engines/GetAllCorpusPretranslations.cs	0.00%	44 Missing ⚠️
...atures/Engines/GetCorpusPretranslationsByTextId.cs	0.00%	43 Missing ⚠️
...ion/Features/Engines/GetCorpusPretranslatedUsfm.cs	69.01%	21 Missing and 1 partial ⚠️
...anslation/Features/Engines/UpdateParallelCorpus.cs	87.73%	10 Missing and 3 partials ⚠️
...anslation/Features/Engines/GetPretranslatedUsfm.cs	91.54%	3 Missing and 3 partials ⚠️
...ion/Features/Engines/GetPretranslationsByTextId.cs	86.04%	3 Missing and 3 partials ⚠️
...c/Serval.Translation/Features/Engines/AddCorpus.cs	93.65%	2 Missing and 2 partials ⚠️
....Translation/Features/Engines/AddParallelCorpus.cs	94.36%	2 Missing and 2 partials ⚠️
...anslation/Features/Engines/PretranslationStatus.cs	71.42%	2 Missing and 2 partials ⚠️
...erval.Translation/Features/Engines/UpdateCorpus.cs	95.18%	2 Missing and 2 partials ⚠️
... and 6 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #925      +/-   ##
==========================================
+ Coverage   65.96%   66.18%   +0.22%     
==========================================
  Files         350      371      +21     
  Lines       21167    21510     +343     
  Branches     2716     2739      +23     
==========================================
+ Hits        13962    14236     +274     
- Misses       6206     6270      +64     
- Partials      999     1004       +5     

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[pmachapman]

@pmachapman partially reviewed 48 files and all commit messages, and made 1 comment.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on pmachapman).