Export embedded chat history (#2329)

frontend/src/locales/de/common.js

frontend/src/locales/en/common.js

frontend/src/locales/es/common.js

frontend/src/locales/fr/common.js

frontend/src/locales/he/common.js

frontend/src/locales/it/common.js

frontend/src/locales/ko/common.js

frontend/src/locales/pt_BR/common.js

frontend/src/locales/ru/common.js

frontend/src/locales/zh/common.js

frontend/src/models/system.js

frontend/src/pages/GeneralSettings/Chats/index.jsx

frontend/src/pages/GeneralSettings/EmbedChats/index.jsx

server/endpoints/system.js

server/utils/helpers/chat/convertTo.js