Add helper for parsing patient CSV ids with BOMs

[mgramigna]

Summary

Add a re-usable helper in a new appUtils file that parses a provided CSV path for mrn column to iterate through patient IDs during extraction.

I want to make sure the approach for this is solid before putting up a bunch of PRs on other repos.

New behavior

None

Code changes

• New helper that does the parsing
  • Throws error if missing a required column or if file isn't found
  • Added to index.js exports
• Update app.js to use new helper
• Unit tests

Testing guidance

Run usual checks and extraction. Output should be the same as it was prior, as we should be getting the same MRNs as before.

[Dtphelan1]

lol the BOM: true got dropped in Julian's PR. whoooppppsss.......
Add that back plz?

[Dtphelan1]

Otherwise I think this looks plenty good and you should consider this conditionally approved by me. HAGS 🏖

[mgramigna]

lol the BOM: true got dropped in Julian's PR. whoooppppsss.......
Add that back plz?

The PR title: "Add helper for parsing patient CSV ids with BOMs"

Phelan:

[dmendelowitz]

This looks good to me, I just had one small comment.