reclassify unsafe-eq test as pos/eq-ne

Author: olhotak

tests/explicit-nulls/pos/eq-ne.scala

@@ -0,0 +1,16 @@
+val s1: String = ???
+val s2: String | Null = ???
+
+def f = {
+  s1 eq s2
+  s2 eq s1
+
+  s1 ne s2
+  s2 ne s1
+
+  s1 eq null
+  s2 eq null
+
+  null eq s1
+  null eq s2
+}