Support trailing comma

^KT-34743 Fixed

compiler/testData/diagnostics/testsWithStdLib/trailingComma/noDisambiguation.kt

@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_PARAMETER
+// !LANGUAGE: +TrailingCommas
+
+fun foo(vararg x: Int) = false
+fun foo() = true
+
+fun main() {
+    val x = foo()
+    val y = foo(<!SYNTAX!>,<!><!SYNTAX!><!>)
+}