Allow use of offline dictionaries or APIs for prepopulation such as Freedict

[stereotypy]

Is your feature request related to a problem? Please describe.
I'm coming from trying out LWT which seems like it's not under active development and a bit dated at this point. I didn't like that to add terms, it basically created a popup to a dictionary and you'd have to manually enter the translation.

Describe the solution you'd like
Freedict (https://freedict.org/downloads/) has a number of free offline dictionaries that could be used for prepopulation if there is an issue finding a free dictionary API (maybe there is one, I don't know).

Describe alternatives you've considered

Typing everything in manually becomes cumbersome. I could cobble together my vocab plus some A1+A2 basic word lists for import via CSV but it would take a long time and is overwhelming.

[jzohrab]

Thanks @stereotypy . This feels like a dup of #228, I'll copy the description above over there. Cheers!