feat: Oauth2

[coeit]

Summary

This PR implements user management via a third-party OAuth2 server.

Changes

Environment

Added the following environment variables to configure the OAuth2 endpoint.

- OAUTH2_TOKEN_URI,  // required
- OAUTH2_PUBLIC_KEY,  // required
- OAUTH2_CLIENT_ID,  // required
- GRAPHIQL_REDIRECT_URI,   // required - defaults to "http://localhost:7000"
- SPA_REDIRECT_URI,  // required - defaults to "http://localhost:8080"    

removed the following environment variables as they are no longer needed.

JWT_SECRET // We use the new OAUTH2_PUBLIC_KEY variable to sign / verify tokens.

Server start up

• refactored migrateDbAndStartServer.sh shell script to accomodate different production / development startups. dev environment can be used by using dev as the first argument on startup. dev environment uses nodemon to start the server and hot reload on changes.
• add setup-keycloak helper to run a keycloak migration on server start up.

server

• add /help route with helpful descriptions on how to get an access_token from the OAuth2 endpoint using password grant
• add /getRolesForOAuth2Token route that returns the roles from a token. A helper function getRoles defines on how to access the user roles from the token. getRoles can be edited by a user if a different implementation of getting roles out of the token is necessary.
• remove /login route

User / Role models

• all static user / role / role_to_user files have been removed.

Related PRs

• ZendroStarterPack: pull/16
• graphql-server-model-codegen: pull/203
• single-page-app: pull/113