[FIR2IR] Properly insert implicit casts to extension receiver in case of intersection smartcast type

^KT-62863 Fixed

compiler/testData/ir/irText/expressions/genericReceiverOnExtensionWithSmartcast.kt

@@ -0,0 +1,14 @@
+// FIR_IDENTICAL
+fun <F : CharSequence> F.bar() {}
+
+inline fun <reified T : CharSequence> test_1(x: Any) {
+    if (x is T) {
+        x.bar()
+    }
+}
+
+fun test_2(x: Any?) {
+    if (x is CharSequence) {
+        x.bar()
+    }
+}