feat: rest api provider for access groups

[abdellah257]

Description

a REST API Provider to fetch access groups

Motivation

additional way to get access groups (used at ILL) using a rest api

Changes:

• New provider at auth/access-group-provider
• Changes to configuration.ts to take into account REST env variables
• env.example updated for a env variables usage example

ACCESS_GROUPS_REST_ENABLED=true
ACCESS_GROUPS_SERVICE_REST_AUTH_KEY="Authorization"
ACCESS_GROUPS_SERVICE_REST_AUTH_VALUE=""
ACCESS_GROUPS_SERVICE_REST_API_URL=""
ACCESS_GROUPS_SERVICE_REST_USER_ID_FIELD=""  # the field to be used from UserPayload

Tests included

• access-group-from-rest-api-call.service.spec.ts

Accidental approve

[Junjiequan]

lgtm, but please double check package-lock.json before you merge this