[JVM IR] Support Suspend Main

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

compiler/tests/org/jetbrains/kotlin/codegen/ir/IrWriteSignatureTestGenerated.java

@@ -656,4 +656,27 @@ public class IrWriteSignatureTestGenerated extends AbstractIrWriteSignatureTest
             runTest("compiler/testData/writeSignature/parameterlessMain/simple.kt");
         }
     }
+
+    @TestMetadata("compiler/testData/writeSignature/suspendMain")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class SuspendMain extends AbstractIrWriteSignatureTest {
+        private void runTest(String testDataFilePath) throws Exception {
+            KotlinTestUtils.runTest(this::doTest, TargetBackend.JVM_IR, testDataFilePath);
+        }
+
+        public void testAllFilesPresentInSuspendMain() throws Exception {
+            KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/writeSignature/suspendMain"), Pattern.compile("^(.+)\\.kt$"), TargetBackend.JVM_IR, true);
+        }
+
+        @TestMetadata("parameterlessSuspendMain.kt")
+        public void testParameterlessSuspendMain() throws Exception {
+            runTest("compiler/testData/writeSignature/suspendMain/parameterlessSuspendMain.kt");
+        }
+
+        @TestMetadata("suspendMain.kt")
+        public void testSuspendMain() throws Exception {
+            runTest("compiler/testData/writeSignature/suspendMain/suspendMain.kt");
+        }
+    }
 }

compiler/tests/org/jetbrains/kotlin/jvm/compiler/WriteSignatureTestGenerated.java

@@ -655,4 +655,27 @@ public class WriteSignatureTestGenerated extends AbstractWriteSignatureTest {
             runTest("compiler/testData/writeSignature/parameterlessMain/simple.kt");
         }
     }
+
+    @TestMetadata("compiler/testData/writeSignature/suspendMain")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class SuspendMain extends AbstractWriteSignatureTest {
+        private void runTest(String testDataFilePath) throws Exception {
+            KotlinTestUtils.runTest(this::doTest, this, testDataFilePath);
+        }
+
+        public void testAllFilesPresentInSuspendMain() throws Exception {
+            KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/writeSignature/suspendMain"), Pattern.compile("^(.+)\\.kt$"), true);
+        }
+
+        @TestMetadata("parameterlessSuspendMain.kt")
+        public void testParameterlessSuspendMain() throws Exception {
+            runTest("compiler/testData/writeSignature/suspendMain/parameterlessSuspendMain.kt");
+        }
+
+        @TestMetadata("suspendMain.kt")
+        public void testSuspendMain() throws Exception {
+            runTest("compiler/testData/writeSignature/suspendMain/suspendMain.kt");
+        }
+    }
 }