[K/N] make :kotlin-native:prepare:kotlin-native-compiler-embeddable tests cacheable

Apply test-inputs-check, declare testData as a task input, and add the
missing dependsOn(:kotlin-native:distInvalidateStaleCaches) to fix the
Gradle implicit-dependency validation error. The test runs the K2Native
compiler in a subprocess, so isNative = true is set to grant the
necessary execute permissions.

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

kotlin-native/prepare/kotlin-native-compiler-embeddable/build.gradle.kts

diff --git a/kotlin-native/prepare/kotlin-native-compiler-embeddable/build.gradle.kts b/kotlin-native/prepare/kotlin-native-compiler-embeddable/build.gradle.kts
index 943cb20..aff062d 100644
--- a/kotlin-native/prepare/kotlin-native-compiler-embeddable/build.gradle.kts
+++ b/kotlin-native/prepare/kotlin-native-compiler-embeddable/build.gradle.kts
@@ -5,6 +5,7 @@
 plugins {
     kotlin("jvm")
     id("project-tests-convention")
+    id("test-inputs-check")
 }
 
 description = "Embeddable JAR of Kotlin/Native compiler"
@@ -111,6 +112,8 @@
 }
 
 projectTests {
+    testData(isolated, "testData")
+
     testTask(jUnitMode = JUnitMode.JUnit4) {
         /**
          * It's expected that test should be executed on CI, but currently this project under `kotlin.native.enabled`
@@ -123,5 +126,9 @@
             nativeDistributionRoot.set(project.nativeDistribution.map { it.root })
             dependsOn(":kotlin-native:distRuntime")
         })
+        dependsOn(":kotlin-native:distInvalidateStaleCaches")
+        testInputsCheck {
+            isNative.set(true)
+        }
     }
 }