JVM: streamline handling of tail-call suspend functions

Just see if every suspend call is followed only by safe instructions or
returns, then insert a suspension point check if there isn't a direct
return.

The first part of this is equivalent to the old implementation, just
refactored. The second part generates strictly more checks; see, for
example, the fixed test, in which the previous implementation failed to
insert a check before a CHECKCAST.

^KT-51818 Fixed

compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirBlackBoxCodegenTestGenerated.java

@@ -12770,6 +12770,12 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
                 runTest("compiler/testData/codegen/box/coroutines/tailCallOptimizations/checkcast.kt");
             }
 
+            @Test
+            @TestMetadata("checkcast2.kt")
+            public void testCheckcast2() throws Exception {
+                runTest("compiler/testData/codegen/box/coroutines/tailCallOptimizations/checkcast2.kt");
+            }
+
             @Test
             @TestMetadata("crossinline.kt")
             public void testCrossinline() throws Exception {