Resolve "Integrate openhive.chat"

Changelog

1. Integrated login to an instance of Rocket Chat with login to Condenser. Done by implementing Oauth 2.0 server on Condenser's back-end. The server can authorize users logged in via passing Hive username and Hive posting key, or logged in via HiveSigner, for Rocket Chat. The server conforms to OpenID Connect 1.0 specification.
2. Upgraded nodejs to 18.14.0 (was 12.22.6). This change was necessary, because command yarn install was not able to install npm packages neither with existing yarn.lock nor when yarn.lock didn't exist. This was occurring on Ubuntu 22.04 and nodejs managed by Volta. Nodejs was upgraded in package.json, in Dockefile, and on Gitlab CI.
3. Introduced file jsconfig.json to enhance intellisense in VS Code editor.
4. Enabled showing unit tests' results in Gitlab UI (pipeline view) by creating Jest reporter on Gitlab CI.
5. Enable source maps in Webpack development configuration file.

Issues

1. Closes #194 (closed)