Executable model - tests from package "integrationtests.operators" fail when run with executable model

When running tests from package org.drools.compiler.integrationtests.operators [1] with executable model, many of them fail (~120 out of ~520). To run the tests with the model, I moved the tests to a separate module in this PR [2], please check the PR description to see how to run them.

[1] https://github.com/kiegroup/drools/tree/d7ad4fb31647b5295c3cbc0321f0d8f89693ec63/drools-compiler/src/test/java/org/drools/compiler/integrationtests/operators
[2] https://github.com/kiegroup/drools/pull/1901