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/wholeProject.kt.after

@@ -0,0 +1,22 @@
+// "Insert lacking comma(s) / semicolon(s) in the whole project" "true"
+
+enum class First {
+    RED, GREEN,
+    BLUE
+}
+
+enum class Second(val code: Int) {
+    NORTH(2), SOUTH(4),
+    EAST(6), WEST(8)
+}
+
+enum class Third {
+    OK {
+        override fun diag(): String = "OK"
+    },
+    ERROR {
+        override fun diag(): String = "Failed"
+    };
+
+    open fun diag(): String = ""
+}