WIP: adds 3.11.snapshot + initial keycloak configuration

[pvgenuchten]

i'm trying to set up a docker-compose with keycloak docker as described in geonetwork/core-geonetwork#4931
it requires latest 3.11 snapshot, which has this PR merged

items pending

• setup keycloak (probably needs to put h2 db configuration on mounted volume)
• setup geonetwork so it uses keycloak
• can we add some default configuration to keycloak, so it loads in a automated way
• wait for 3.12.0 release, or consider a mechanism to always take latest nightly

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