[REQ][JAVA] Replace apache oltu with scribejava for java generator

Created by: valmoz

Description Currently, the Java generator uses Oltu to perform oauth requests.

Apache Oltu has been moved into the Attic in April 2018, so it's not actively maintained anymore. It would be great to replace Oltu with Scribejava (or at least to add an option to select the oauth library), like already did for the java-feign generator in this issue: https://github.com/OpenAPITools/openapi-generator/issues/8297

openapi-generator version 5.2.1