SF-3163a Forward compatibility with the upcoming draft source arrays

[pmachapman]

This is a pre-requisite for #3508 to allow older clients running this logic to still view draft sources when Sf-3163 is deployed.

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This change is 

[codecov]

Codecov Report

❌ Patch coverage is 0% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.47%. Comparing base (93615cb) to head (2c11d2b).
⚠️ Report is 1 commits behind head on master.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
.../src/app/translate/draft-generation/draft-utils.ts	0.00%	5 Missing and 1 partial ⚠️
...c/SIL.XForge.Scripture/ClientApp/src/type-utils.ts	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3531      +/-   ##
==========================================
- Coverage   82.48%   82.47%   -0.02%     
==========================================
  Files         615      615              
  Lines       36914    36921       +7     
  Branches     6009     6012       +3     
==========================================
  Hits        30450    30450              
- Misses       5579     5584       +5     
- Partials      885      887       +2     

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[Nateowami]

@Nateowami reviewed 2 of 2 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @pmachapman)