Support parameterless and suspend main functions in multifile classes

#KT-26574 Fixed

compiler/testData/codegen/bytecodeListing/main/multifileSuspend.kt

@@ -0,0 +1,6 @@
+// WITH_RUNTIME
+@file:JvmMultifileClass
+@file:JvmName("Foo")
+package Hello
+
+suspend fun main(args: Array<String>) {}

compiler/testData/codegen/bytecodeListing/main/multifileSuspend.txt

@@ -0,0 +1,18 @@
+@kotlin.Metadata
+public final class Hello/Foo {
+    public final static @org.jetbrains.annotations.Nullable method main(@org.jetbrains.annotations.NotNull p0: java.lang.String[], @org.jetbrains.annotations.NotNull p1: kotlin.coroutines.Continuation): java.lang.Object
+    public synthetic static method main(p0: java.lang.String[]): void
+}
+
+@kotlin.Metadata
+synthetic final class Hello/Foo__MultifileSuspendKt$$$main {
+    private final field args: java.lang.String[]
+    synthetic method <init>(p0: java.lang.String[]): void
+    public synthetic final method invoke(p0: java.lang.Object): java.lang.Object
+}
+
+@kotlin.Metadata
+synthetic final class Hello/Foo__MultifileSuspendKt {
+    public final static @org.jetbrains.annotations.Nullable method main(@org.jetbrains.annotations.NotNull p0: java.lang.String[], @org.jetbrains.annotations.NotNull p1: kotlin.coroutines.Continuation): java.lang.Object
+    public synthetic static method main(p0: java.lang.String[]): void
+}

compiler/testData/integration/smoke/helloAppSuspendMainInMultifile/hello.compile.expected

@@ -0,0 +1 @@
+Return code: 0

compiler/testData/integration/smoke/helloAppSuspendMainInMultifile/hello.kt

@@ -0,0 +1,37 @@
+@file:JvmMultifileClass
+@file:JvmName("Foo")
+package Hello
+
+import kotlin.concurrent.thread
+import kotlin.coroutines.suspendCoroutine
+import kotlin.coroutines.resume
+
+@kotlin.jvm.Volatile
+private var result = ""
+@kotlin.jvm.Volatile
+private var callback: Function0<Unit>? = null
+
+suspend fun appendAndSuspend(s: String) {
+    result += s
+
+    suspendCoroutine<Unit> { continuation ->
+        callback = {
+            continuation.resume(Unit)
+        }
+    }
+}
+
+suspend fun main(args: Array<String>) {
+    thread(isDaemon = true) {
+        while (true) {
+            val c = callback
+            c?.invoke()
+            Thread.sleep(500)
+        }
+    }
+
+    appendAndSuspend(args[0])
+    appendAndSuspend(args[1])
+    println(result)
+    callback = null
+}

compiler/testData/integration/smoke/helloAppSuspendMainInMultifile/hello.run.expected

@@ -0,0 +1,4 @@
+OUT:
+OK
+
+Return code: 0