Quick fix for enum entry delimiter syntax fix, together with a set of tests.

Possible NPE in getNextSiblingIgnoringWhitespace fixed. Some warnings also removed.
Last comma is replaced by semicolon. Comments are taken into account.

idea/testData/quickfix/migration/enumDelimiter/noDelimiterWithInitializer.kt

@@ -0,0 +1,8 @@
+// "Insert lacking comma(s) / semicolon(s)" "true"
+
+enum class MyEnum(val z: Int) {
+    A: MyEnum(3)
+    B<caret>: MyEnum(7)
+    C: MyEnum(12)
+    fun foo() = z * 2
+}