Refactor DL-Learner to use builder pattern or similar

[SimonBin]

Alternatively throw exceptions in all public methods, whether they are pre-init or post-init methods. Or research other options to stop incorrect DL-Learner usage (by which I mean: calling set Methods after .init or calling methods before .init has been done) Sample exception I added for some specific case in RhoDRDown: https://github.com/AKSW/DL-Learner/blob/94da38d7c1e1adc8ee7613c1938a3a550a0d4a23/components-core/src/main/java/org/dllearner/refinementoperators/RhoDRDown.java#L472