Add multi-language support

[lony2003]

Hi! I'm a user and developer from China and I want to translate this program into Chinese. Have you schedued to implement the multi-language support? If not, I would like to give some help.

[lakhansamani]

@lony2003 some help would be really helpful
Need to work on translation model.
I can write a detailed RFC for that if you like

[lony2003]

@lakhansamani Well, that would be greate to me. In my conception, I would like to use react-intl-universal to achive that since react-intl is huge and we just need some features of it.

To make the whole process seamless, I think I'll make this process into three parts.

• Import the libraries and replace strings in this program. All the strings in the program will be replaced to this format like

intl.get('HELLO', { name }).d(`Hello, ${name}`);

• Generate the messages list with react-intl-universal-extract, a tool from react-intl-universal. It will generate a json file like

{
  "hello1": "Hello World",
  "hello2": "Hello {name}",
}

and you can upload it to some localization platform like weblate and translate it. Then get the translated json from it.

• Add some select language and help us translate stuff in pages.

This process can solve most of the problem except "RTL" direction of the page, but it can be implement later.