[Gradle] Replace TaskProvider.flatMap with map { it.get() }

flatMap doesn't support implicit task dependencies due to bug:
https://github.com/gradle/gradle/issues/25645

However `map { it.get() }` works.

^KT-63011 Verification Pending

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/targets/native/configureBinaryFrameworks.kt

@@ -55,7 +55,9 @@ internal fun Project.createFrameworkArtifact(binaryFramework: Framework, linkTas
         }
     })
 
-    addFrameworkArtifact(frameworkConfiguration, linkTask.flatMap { it.outputFile })
+    // Can't use flatMap here because of https://github.com/gradle/gradle/issues/25645
+    val linkTaskOutputProvider = linkTask.map { it.outputFile.get() }
+    addFrameworkArtifact(frameworkConfiguration, linkTaskOutputProvider)
 }
 
 internal val CreateFatFrameworksSetupAction = KotlinProjectSetupCoroutine {