GSGGR-156 Add OIDC authentication flow for the geoshop frontend

[lanseg]

This pull request adds initializes an open-id authentication for the geoshop-frontend, but to make it fully working there should be an update on the geoshop-backend side. Here is the frontend flow:

1. Angular application authenticates user with an OIDC provider and sends access token to the backend
2. Backend gets user information from the OIDC provider by token, creates new user or update existing
3. Backend issues refresh and access tokens and returns them to the frontend.
   • Thant makes possible to keep name/password login and token refresh working.

If no OIDC provider is configured, OIDC authentication is disabled (see screenshots).