8267043: IntelliJ project doesn't handle generated sources correctly

Reviewed-by: chegar, erikj

Author: mcimadamore

make/ide/idea/jdk/template/misc.xml

@@ -12,7 +12,7 @@
       <target file="file://###ROOT_DIR###/make/ide/idea/jdk/build.xml" name="images" />
     </ant>
   </component>
-  <component name="ProjectRootManager" version="2" languageLevel="JDK_1_9" assert-keyword="true" jdk-15="true">
-    <output url="file://###BUILD_DIR###" />
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_16" assert-keyword="true" jdk-15="true">
+    <output url="file://###BUILD_DIR###/idea" />
   </component>
 </project>