AddJavadocIntention: disable at field initializers

Add JavaDoc was available at initializer in some rare cases, e.g. "String foo = b<caret>ar;" (initializer is a simple reference), which was inconsistent and confusing (will the action add JavaDoc to "foo" or to "bar"?

java/java-tests/testData/codeInsight/addJavadoc/beforeFieldAtInitializer.java

@@ -0,0 +1,8 @@
+// "Add Javadoc" "false"
+
+class Test {
+
+  String foo = "xyz";
+  String bar = f<caret>oo;
+
+}