Update dictionaries within the app

[aaronhktan]

Is your feature request related to a problem? Please describe.
Instead of throwing a user into the web browser to download a dictionary file, and then importing it, integrate it with the application's UI.

Describe the solution you'd like
This would mean checking the dictionary version, comparing it with a manifest on the website (similar to https://jyutdictionary.com/static/updates/v1/versions_info.json for update info), and downloading -> installing the dictionary.