Introduce Variable: Compare receivers (both implicit and explicit) when looking for expression occurrences

#KT-4819 Fixed

idea/testData/refactoring/introduceVariable/nonEquivalentReceivers.kt

@@ -0,0 +1,17 @@
+class A {
+    val value : Int = 0
+}
+
+fun foo(body: A.() -> Unit) {}
+
+fun bar() {
+    foo {
+        print(<selection>value</selection>)
+        print(value)
+    }
+
+    foo {
+        print(value)
+        print(value)
+    }
+}

idea/testData/refactoring/introduceVariable/nonEquivalentReceivers.kt.after

@@ -0,0 +1,18 @@
+class A {
+    val value : Int = 0
+}
+
+fun foo(body: A.() -> Unit) {}
+
+fun bar() {
+    foo {
+        val i = value
+        print(i)
+        print(i)
+    }
+
+    foo {
+        print(value)
+        print(value)
+    }
+}