Frontend: fixed explicit receiver kind for dynamic call with implicit dispatch receiver.

Additionally added tests for other cases.

compiler/testData/resolvedCalls/dynamic/implicitReceiverIsExtensionReceiver.txt

@@ -0,0 +1,14 @@
+fun dynamic.foo() {}
+
+fun dynamic.bar() {
+    <caret>foo()
+}
+
+
+Resolved call:
+
+Resulting descriptor: fun dynamic.foo(): Unit defined in root package
+
+Explicit receiver kind = NO_EXPLICIT_RECEIVER
+Dispatch receiver = NO_RECEIVER
+Extension receiver = ('Nothing'..'Any?')Ext{fun dynamic.bar(): Unit defined in root package}