Add dictionary support

[gracewhitney]

• Get word lists (format?)
• dictionaries setting in new game creation
• If a dictionary is set, validate words

Alternatively, consider using a dictionary API (or parse a dictionary website)

[gracewhitney]

This has been partially completed: words that are not found via https://api.dictionaryapi.dev/ will display a validation error which does not block their play.

Further expansion: add native functionality for:

• uploading a wordlist, e.g. via management command, which will construct and save a DAWG for word lookup (open question: should these live in codebase source? What file format?)
• Option during game creation to pick from available word lists. Maybe also separate option to choose whether invalid words should block play
• API endpoint to check word against chosen wordlists for game
• Upload own wordlist?

[gracewhitney]

Native functionality should also support blanks