[Native][tests] Don't treat any compiler test task as up-to-date

There are number of problems with up-to-date checks in tests, leading to
a test binary not being rebuilt or rerun when a developer expects it to.

Things became worse after updating to Gradle 7+:
test binary run tasks are considered up-to-date if the test data
has been changed, even after clean.

Even before Gradle 7+, we've observed other similar undesirable effects:
for example, if the compiler has been changed, tasks building
test binaries are still up-to-date.

So it was decided to workaround all possible similar problems by forcing
all test tasks in the :native:native.tests project to be not up-to-date.

This project should contain only test tasks, so this workaround
seems pretty natural -- it is just "tests aren't up-to-date".

native/native.tests/build.gradle.kts

@@ -62,7 +62,13 @@ enum class TestProperty(shortName: String) {
 fun Test.setUpBlackBoxTest(tag: String) {
     if (kotlinBuildProperties.isKotlinNativeEnabled) {
         dependsOn(":kotlin-native:dist")
+
         workingDir = rootDir
+        outputs.upToDateWhen {
+            // Don't treat any test task as up-to-date, no matter what.
+            // Note: this project should contain only test tasks, including ones that build binaries, and ones that run binaries.
+            false
+        }
 
         maxHeapSize = "6G" // Extra heap space for Kotlin/Native compiler.
         jvmArgs("-XX:MaxJavaStackTraceDepth=1000000") // Effectively remove the limit for the amount of stack trace elements in Throwable.