Remove useless includeTestSource flag from ProjectRootsUtil
++
++
++ JetSourceFilterScope.java
++ IDELightClassGenerationSupport.java
Refactor ProjectRootsUtil

Account for cases when there library source files under classes root
++ ProjectRootsUtil.kt
TEST: Enable basic highlighting in decompiled kotlin files
Enable DeclarationHintSupport for decompiled kotlin files
++ IDELightClassGenerationSupport.java