Don't highlight "replace with +=" for read-only collections

Related to KT-20626

idea/testData/inspectionsLocal/replaceWithOperatorAssignment/list.kt

@@ -0,0 +1,9 @@
+// WITH_RUNTIME
+// HIGHLIGHT: INFORMATION
+
+fun foo() {
+    var list = listOf(1, 2, 3)
+    // Should not be highlighted because it's the way we use to say explicitly
+    // "yes, we want to re-assign this immutable list"
+    list <caret>= list + 4
+}

idea/testData/inspectionsLocal/replaceWithOperatorAssignment/list.kt.after

@@ -0,0 +1,9 @@
+// WITH_RUNTIME
+// HIGHLIGHT: INFORMATION
+
+fun foo() {
+    var list = listOf(1, 2, 3)
+    // Should not be highlighted because it's the way we use to say explicitly
+    // "yes, we want to re-assign this immutable list"
+    list += 4
+}

idea/testData/inspectionsLocal/replaceWithOperatorAssignment/mutableList.kt

@@ -0,0 +1,7 @@
+// WITH_RUNTIME
+// HIGHLIGHT: GENERIC_ERROR_OR_WARNING
+
+fun foo() {
+    val list = mutableListOf(1, 2, 3)
+    list <caret>= list + 4
+}

idea/testData/inspectionsLocal/replaceWithOperatorAssignment/mutableList.kt.after

@@ -0,0 +1,7 @@
+// WITH_RUNTIME
+// HIGHLIGHT: GENERIC_ERROR_OR_WARNING
+
+fun foo() {
+    val list = mutableListOf(1, 2, 3)
+    list += 4
+}