Add "Suspicious collection reassignment" inspection #KT-20626 Fixed

idea/testData/inspectionsLocal/suspiciousCollectionReassignment/mutableSet.kt

@@ -0,0 +1,7 @@
+// PROBLEM: none
+// ERROR: Assignment operators ambiguity: <br>public operator fun <T> Set<Int>.plus(element: Int): Set<Int> defined in kotlin.collections<br>@InlineOnly public inline operator fun <T> MutableCollection<in Int>.plusAssign(element: Int): Unit defined in kotlin.collections
+// WITH_RUNTIME
+fun test() {
+    var set = mutableSetOf(1)
+    set <caret>+= 2
+}