Fixes for generating alignments alongside pretranslations

[Enkidu93]

• Make align_pretranslations configurable in build_options
• Don't try to ingest non-existent pretranslation.src.json properties

Related to sillsdev/serval#663

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This change is 

[Enkidu93]

While I was digging into this testing it and trying to get some sample output pretranslation jsons, I realized that it's not particularly straightforward to run machine.py nmt jobs locally end-to-end. Is there an issue already for making a dummy translation job for testing? What's in the launch.json doesn't work well locally and the code isn't set up for using the cpu.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.87%. Comparing base (0ff0f8d) to head (bdd0ad1).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #179   +/-   ##
=======================================
  Coverage   88.87%   88.87%           
=======================================
  Files         282      282           
  Lines       16951    16951           
=======================================
  Hits        15065    15065           
  Misses       1886     1886           

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[ddaspit]

Reviewed 1 of 2 files at r1, 4 of 4 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @isaac091)