[FEAT] - Add file upload option

For each language there should be a default set of popular words and phrases, currently in a file for English, but eventually in a database. But there should be an option for the user to upload a file of their text to be used to populate the alphabetical list and the Proper Nouns (need a better name than "Proper Nouns").

Eventually, the user will be able to switch to different uploaded text, e.g., one for professional communication, one for friends, and one for family.

Start by locating the current English word-and-phrase file and the code that builds the alphabetical list and Proper Nouns list. Define the upload flow, how uploaded text replaces or supplements the defaults, and how users switch between texts; the issue is done when these behaviors are specified and verified in the application.

Written by the indexing model from the issue text.