[Security] OAuth configuration for SAP BTP Cloud Foundry

[ThuF]

Provide OAuth configuration for SAP BTP Cloud Foundry deployments.

Docs:

• https://docs.spring.io/spring-security/reference/servlet/oauth2/login/core.html
• https://spring.io/guides/tutorials/spring-boot-oauth2/
• https://www.baeldung.com/spring-security-5-oauth2-login

Keycloak config:

• components/security-keycloak/src/main/java/org/eclipse/dirigible/components/security/keycloak/KeycloakConfiguration.java#L20
• components/security-keycloak/src/main/java/org/eclipse/dirigible/components/security/keycloak/KeycloakSecurityConfiguration.java#L28