[K/N] Migrate most simple filecheck tests to new infra

^KT-62157


Merge-request: KT-MR-12376
Merged-by: Vladimir Sukharev <Vladimir.Sukharev@jetbrains.com>

compiler/testData/codegen/box/fileCheck/kt49847_sam_Int.kt

@@ -0,0 +1,21 @@
+// TARGET_BACKEND: NATIVE
+// FILECHECK_STAGE: CStubs
+
+fun interface Foo {
+    fun bar(x: Int): Int
+}
+
+fun baz(x: Int): Int = x.hashCode()
+
+// CHECK-LABEL: define %struct.ObjHeader* @"kfun:#box(){}kotlin.String"
+// CHECK-OPT-NOT: Int-box
+// CHECK-DEBUG: Int-box
+// CHECK-NOT: Int-unbox
+// CHECK-LABEL: epilogue:
+fun box(): String {
+    val foo: Foo = Foo(::baz)
+    val result = foo.bar(42)
+    return if( result == 42 )
+        "OK"
+    else "FAIL: $result"
+}