Split system messages to separated JSON files

[winstonsung]

(as title described)

Reason: Prevent hardcoded strings.

See https://github.com/wikimedia/mediawiki/blob/38066e5/languages/i18n/preferences/zh-hant.json

[iach526526]

Do you mean the bot's reply strings should be written in a separate JSON file?

[winstonsung]

Yeah, similar concept.

Example: https://github.com/wikimedia/mediawiki/blob/38066e5/languages/i18n/preferences/zh-hant.json

[winstonsung]

(Added in src layout directory structure, implement later.)

[YuevUwU]

mark solution commit plz

[YuevUwU]

Not resolved on 0.1.14, re-opened