[#232] Draft: Resolve "Move CERN specifics to Config"

Closes #232

Follows https://gitlab.cern.ch/push-notifications/notifications-design/-/issues/55#web-portal-some-fixes-in-httpsgitlabcernchpush-notificationsweb-portal-issues232

Added env:

REACT_APP_OAUTH_SSO_LOGOUT_URL=https://auth.cern.ch/auth/realms/cern/protocol/openid-connect/logout?redirect_uri=

# (CERN) Specific features configuration in Global part: FEATURE_*
FEATURE_SEND_FROM_EGROUP=true
FEATURE_ARCHIVES=true
FEATURE_INDICO=true