NI: Add regression test for KT-38799

The issue has been fixed by introducing the modified postponed arguments analysis (KT-37952)

compiler/testData/diagnostics/testsWithStdLib/inference/completion/postponedArgumentsAnalysis/kt38799.kt

@@ -0,0 +1,11 @@
+// FIR_IDENTICAL
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_ANONYMOUS_PARAMETER
+
+fun main() {
+    fun foo(m: Map<String, (Array<Int>) -> Unit>) {}
+    fun mySort(a: Array<Int>) {}
+    foo(m = mapOf(
+        "mySort" to ::mySort,
+        "mergeSort" to { a: Array<Int> -> }
+    ))
+}

compiler/testData/diagnostics/testsWithStdLib/inference/completion/postponedArgumentsAnalysis/kt38799.txt

@@ -0,0 +1,3 @@
+package
+
+public fun main(): kotlin.Unit