Unify import from data*import.js scripts into data*.ts

[UmbralAlderman]

There are a few steps involved here

1. Create new functions to make an unmodified local cache of the JSON source files.
2. Migrate markdown conversion into importFromData*() methods. (introducing a new markdown parser dependency)
3. Update i18n files in importFromData*() methods.

importFromData*() may make more sense as the name of the methods from 1., in which case the methods from 2. should be renamed into something like rebuildData*Compendia()

Bonus cleanup: it'd be great if the methods which construct compendia could handle unlocking existing ones, creating absent ones, and relocking them after update.

[ben]

Realizing there's more to do here, so I'm reopening this.