Create service as a separate module

[muke1908]

https://github.com/muke1908/chat-e2ee/blob/master/client/src/service/index.js

Move out this module out of client folder, consume it as package in client folder.
for example, in client package.json:
@chate2ee/service: "file: ../service"

• make it publisable as separate package.

It will unlock the possibility to make this package available separately and allow to build chat app on different web-client.

[muke1908]

#283