This adds supports for (parameterless) suspend main entry points for
the JVM IR backend.
In case main is a suspend function, it gains a continuation during
lowering, so we simply generate a plain old `public static void
main(String[] args)`. This entry point invokes `suspend main` via
`kotlin.coroutines.jvm.internal.RunSuspendKt#runSuspend`.
This PR introduces `runSuspend` as a built-in, and generates the
following `main`, passing `args` as appropriate:
```
fun main(args: Array<String>) {
runSuspend { main(args) }
}
```
The phase ordering has been reshuffled countrary to previous
discussion on #2780, as the MainMethodGeneration pass now introduces lambdas in
the IR. Hence, it has to run before InventNamesForLocalClasses, yet
still after JvmOverloadsAnnotations.
Some dead code was discovered in AddContinuationLowering
Kristoffer Andersen
55aafb3430