OIDC integration with INDICO IAM

[garciagenrique]

Currently the extension uses reana-user credential to get identified toward the instance (Server Name and Access Token provided by the reana instance).

A very interesting feature would be to develop an OIDC hook that grant access to Reana, after user identification to the upstream Identity Provider - in the VRE case the ESCAPE IAM instance that also grant access to the VRE platform.