Add exit point highlighting for accessors (KT-21318)

#KT-21318 Fixed

idea/testData/exitPoints/getter.kt

@@ -0,0 +1,12 @@
+val Any?.foo: Int
+    get() {
+        this?.let {
+            <caret>return 1
+        }
+        return 2
+    }
+
+public inline fun <T> T.let(block: (T) -> Unit) {}
+
+//HIGHLIGHTED: return 1
+//HIGHLIGHTED: return 2

idea/testData/exitPoints/inline3.kt

@@ -0,0 +1,11 @@
+fun Any?.foo(): Int {
+    this?.let {
+        <caret>return 1
+    }
+    return 2
+}
+
+public inline fun <T> T.let(block: (T) -> Unit) {}
+
+//HIGHLIGHTED: return 1
+//HIGHLIGHTED: return 2