Add some tests on adapted references with varargs and reflection

Also rename "varargAndDefaults" test directory to "adaptedReferences"

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

@@ -1,19 +1,18 @@
 // TARGET_BACKEND: JVM
 // IGNORE_BACKEND_FIR: JVM_IR
 // WITH_RUNTIME
+
 import kotlin.reflect.KCallable
 
-fun checkUnit(label: String, fn: () -> Unit) {
+private fun check(label: String, fn: Any) {
     if (fn is KCallable<*>) {
         throw AssertionError("$label is KCallable, ${fn::class.java.simpleName}")
     }
 }
 
-fun checkAny(label: String, fn: () -> Any) {
-    if (fn is KCallable<*>) {
-        throw AssertionError("$label is KCallable, ${fn::class.java.simpleName}")
-    }
-}
+fun checkUnit(label: String, fn: () -> Unit) = check(label, fn)
+fun checkAny(label: String, fn: () -> Any) = check(label, fn)
+fun checkOneElementForVararg(label: String, fn: (Int) -> Unit) = check(label, fn)
 
 fun withDefaults(a: Int = 1, b: Int = 2) {}
 fun withVarargs(vararg xs: Int) {}
@@ -33,5 +32,8 @@ fun box(): String {
     checkUnit("::CWithDefaults", ::CWithDefaults)
     checkUnit("::CWithVarargs", ::CWithVarargs)
 
+    checkOneElementForVararg("::withVarargs", ::withVarargs)
+    checkOneElementForVararg("::CWithVarargs", ::CWithVarargs)
+
     return "OK"
 }

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

@@ -0,0 +1,22 @@
+// TARGET_BACKEND: JVM
+// WITH_RUNTIME
+
+import kotlin.reflect.KCallable
+
+private fun check(label: String, fn: Any) {
+    if (fn !is KCallable<*>) {
+        throw AssertionError("$label is not KCallable, ${fn::class.java.simpleName}")
+    }
+}
+
+fun checkVarargAsArray(label: String, fn: (IntArray) -> C) = check(label, fn)
+
+fun withVarargs(vararg xs: Int): C = C(*xs)
+class C(vararg xs: Int)
+
+fun box(): String {
+    checkVarargAsArray("::withVarargs", ::withVarargs)
+    checkVarargAsArray("::C", ::C)
+
+    return "OK"
+}