Add Customized language support for Jetbrains IDE plugin

[coldsmirk]

Currently, the shortcut commands provided by the plugin (such as code interpretation, issue fixing, test generation, etc.) are all in English. This results in Copilot Chat responding in English as well, which is not user-friendly for users whose native language is not English.

It is hoped that there can be an option to customize the language used by Copilot Chat for responses or to customize the shortcut commands.