For each parameter not used: handle char sequences correctly

An enhancement for KT-27209

idea/testData/inspectionsLocal/forEachParameterNotUsed/string.kt.after

@@ -0,0 +1,6 @@
+// WITH_RUNTIME
+// FIX: Replace with 'repeat()'
+
+fun test(s: String) {
+    repeat(s.length) {}
+}