[JVM_IR] Fix inlining of callable references to extension methods.

Check directly that the referenced function is an extension
function instead of relying on the annotation on the type.

^ KT-47988 Fixed.

compiler/testData/codegen/box/callableReference/kt47988.kt

@@ -0,0 +1,17 @@
+class A(var x: String)
+
+fun f(s: String): String {
+    fun A.localX() {
+        x = s + "K"
+    }
+
+    val a: A = A("FAIL")
+    a.apply(A::localX)
+    if (a.x != "OK") return a.x
+    a.apply { localX() }
+    return a.x
+}
+
+fun box(): String {
+    return f("O")
+}