Add task to run only JUnit 5 KGP tests.

^KT-45744 In Progress

libraries/tools/kotlin-gradle-plugin-integration-tests/build.gradle.kts

@@ -197,7 +197,6 @@ tasks.withType<Test> {
     useAndroidSdk()
 
     maxHeapSize = "512m"
-    maxParallelForks = (Runtime.getRuntime().availableProcessors() / 4).coerceAtLeast(1)
     useJUnitPlatform()
 
     testLogging {
@@ -233,3 +232,14 @@ tasks.withType<Test> {
         })
     }
 }
+
+tasks.register<Test>("kgpJunit5Tests") {
+    group = "Verification"
+    description = "Run only JUnit 5 tests for Kotlin Gradle Plugin"
+    maxParallelForks = (Runtime.getRuntime().availableProcessors() / 4).coerceAtLeast(1)
+
+    useJUnitPlatform {
+        includeTags("JUnit5")
+        includeEngines("junit-jupiter")
+    }
+}