enable access to aai refresh token

Motivation:

Each time a aai access token is needed, we need to authenticate again to obtain a new access token. However, this is not necessary since we can use the refresh token, provided one is available to obtain a new access_token.

Modification:

• initialise OAuth2AuthorizedClientService by using constructor instead of autowiring
• add a GET controller and a link that can be use to get the refresh token
• add to the list of scope offline_access to request for the refresh token from the auth server (that is Helmholtz AAI server).

Result: Refresh token can now be obtain

Target: master Acked-by: Review-at: https://gitlab.hzdr.de/hifis-technical-platform/helmholtz-marketplace-server/-/merge_requests/12