Fix maven tests.
IDEA-95802: Extract method suggests expressions to extract
don't suggest to shorten reference to inner class if 'insert inner class import' option is off
tests
cleanup
IDEA-99777: 'null' expression should have PsiType.NULL type
dead code
IDEA-102379 Gradle: Don't refresh a project on disabling auto-import

1. Don't refresh a project on disabling auto-import;
2. Auto-import only known project structure changes on enabling auto-import (don't perform new gradle project refresh);
per-config file caching