Add some tests on adapted references with varargs and reflection

Also rename "varargAndDefaults" test directory to "adaptedReferences"

compiler/testData/codegen/box/callableReference/adaptedReferences/varargWithDefaultValue.kt

@@ -0,0 +1,15 @@
+// !LANGUAGE: +NewInference +FunctionReferenceWithDefaultValueAsOtherType
+// IGNORE_BACKEND_FIR: JVM_IR
+
+fun foo(x: Int, s: Int, vararg y: CharSequence = arrayOf("Aaa")): String =
+        if (y.size == s && y[0].length == x) "OK" else "Fail"
+
+fun use0(f: (Int, Int) -> String): String = f(3, 1)
+fun use1(f: (Int, Int, String) -> String): String = f(5, 1, "Bbbbb")
+fun use2(f: (Int, Int, String, String) -> String): String = f(5, 2, "Bbbbb", "Ccccc")
+
+fun box(): String {
+    if (use0(::foo) != "OK") return "Fail0"
+    if (use1(::foo) != "OK") return "Fail1"
+    return use2(::foo)
+}