Refactoring: Move blackbox tests about unsigned types to new directory

compiler/testData/codegen/box/inlineClasses/checkBasicUnsignedLiterals.kt

@@ -1,16 +0,0 @@
-// !LANGUAGE: +InlineClasses
-// !SKIP_METADATA_VERSION_CHECK
-// WITH_UNSIGNED
-
-fun box(): String {
-    val u1 = 1u
-    val u2 = 2u
-    val u3 = u1 + u2
-    if (u3.toInt() != 3) return "fail"
-
-    val max = 0u.dec().toLong()
-    val expected = Int.MAX_VALUE * 2L + 1
-    if (max != expected) return "fail"
-
-    return "OK"
-}

compiler/testData/codegen/box/inlineClasses/unsignedLiteralsWithSignedOverflow.kt

@@ -1,10 +0,0 @@
-// !LANGUAGE: +InlineClasses
-// !SKIP_METADATA_VERSION_CHECK
-// WITH_UNSIGNED
-
-fun box(): String {
-    val u1: UByte = 255u
-    if (u1.toByte().toInt() != -1) return "fail"
-
-    return "OK"
-}