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

idea/testData/quickfix/suspiciousCollectionReassignment/joinWithInitializer/notLocal.kt

@@ -0,0 +1,15 @@
+// "Join with initializer" "false"
+// TOOL: org.jetbrains.kotlin.idea.inspections.SuspiciousCollectionReassignmentInspection
+// ACTION: Replace overloaded operator with function call
+// ACTION: Replace with ordinary assignment
+// WITH_RUNTIME
+class Test {
+    var list = createList()
+
+    fun test(otherList: List<Int>) {
+        // comment
+        list <caret>+= otherList
+    }
+
+    fun createList(): List<Int> = listOf(1, 2, 3)
+}