Support variadic functions

[Dominaezzz]

At the moment Kotlin/Native doesn't support forwarding args to variadic C functions.

fun ImGui.text(fmt: String, varags args: Any?) {
    igText(fmt, *args)
}

result in

e:(...path...): When calling variadic C functions spread operator is supported only for *arrayOf(...)

[Dominaezzz]

Also consider voting for these.

• https://youtrack.jetbrains.com/issue/KT-4859
• https://youtrack.jetbrains.com/issue/KT-21644

They would eliminate the need for variadic support in kotlin-imgui.