Refactor Translation Logic and Make It More Testable

[pjkaufman]

Fixes #689

There were some things noted about the translation helper that needed work. So I went ahead and gave it some more love to make it easier to work with logic-wise. There are still things that can be improved around it, but the helper methods and logic that was refactored should make things a decent bit clearer and easier to test.

Some tests were added to help make sure issues around locale files not mapping properly between their short code value and the file name could be caught earlier.

Changes Made:

• Added UTs to make sure all locales that exist refer to a unique file that exists in the locales directory
• Added a type for partial locales
• Updated docs for adding a language to include info and a rationale about why the locale to file name mapping is important
• Refactored esbuild setup to make things simpler to use and make sure that there would be less logic that needs updating when a change to the config is made
• Setup some more helper methods around translations like getting the file referenced by a language short code/locale
• Added a couple of validators for user input for the translation helper that helps with input validation and not needing to nest ifs
• Refactored some translation helper logic to make sure common parts got reused better and helped clear up some complexity by removing if statements where possible