Get test-sets/integrationTest task working again

Plugin config not working in `subprojects` block: unbroken-dome/gradle-testsets-plugin#109 (comment)
So applying it in the subproject `build.gradle.kts`... means duplicate
code if there's more than 1 subproject...

There are other ways to register `integrationTest` task: https://stackoverflow.com/questions/52904603/integration-tests-with-gradle-kotlin-dsl
But it's a lot more code, and none of them add `jacoco` for free.

README.md

@@ -13,7 +13,7 @@ template repository for Java projects using Gradle
 - Automatic code formatting via [Spotless](https://github.com/diffplug/spotless)
 - Code style analysis via [Checkstyle](https://github.com/checkstyle/checkstyle)
 - Static analysis via [SpotBugs](https://spotbugs.github.io/)
-- Unit and integration test support via JUnit 5 and [TestSets plugin](https://github.com/unbroken-dome/gradle-testsets-plugin)
+- Unit and integration test support via [JUnit 5](https://junit.org/junit5/) and [TestSets plugin](https://github.com/unbroken-dome/gradle-testsets-plugin)
 - Code coverage reporting via [Codecov](https://codecov.io/)
 - Dependency upgrades via [Renovate bot](https://renovatebot.com)
 

build.gradle.kts

@@ -14,7 +14,6 @@ plugins {
   id("com.diffplug.gradle.spotless") version "6.19.0" apply (false)
   id("com.github.spotbugs") version "5.0.14" apply (false)
   id("com.asarkar.gradle.build-time-tracker") version "4.3.0"
-  id("org.unbroken-dome.test-sets") version "4.0.0" apply (false)
 }
 
 allprojects {
@@ -102,9 +101,6 @@ subprojects {
     }
   }
 
-  // Integration test support
-  // TODO test-set plugin
-
   dependencies {
     val log4jVersion = "2.20.0"
     val guavaVersion = "32.0.1-jre"

hello-world/build.gradle.kts

@@ -0,0 +1,5 @@
+plugins {
+  id("org.unbroken-dome.test-sets") version "4.0.0"
+}
+
+testSets { create("integrationTest") }