Light class codegen: do not apply compiler plugins

Applying plugins leads to failures when matching members in LazyLightClassDataHolder
    because plugins rely on analysis results
This decision has its drawbacks (java won't see results of plugin execution)
    but more work on light classes is needed if we want to support this usecase
We can argue that plugins should only generate synthetic members
    but there is no such restriction atm

compiler/backend/src/org/jetbrains/kotlin/codegen/ImplementationBodyCodegen.java

@@ -365,6 +365,8 @@ public class ImplementationBodyCodegen extends ClassBodyCodegen {
         if (context.closure != null)
             genClosureFields(context.closure, v, typeMapper);
 
+        if (state.getClassBuilderMode() == ClassBuilderMode.LIGHT_CLASSES) return;
+
         for (ExpressionCodegenExtension extension : ExpressionCodegenExtension.Companion.getInstances(state.getProject())) {
             extension.generateClassSyntheticParts(this);
         }