Moved workflow samples out of .github/workflows

The `.github/workflows` directory has additional permissions attached, preventing these
files from being by the Upgrade Gradle Wrapper plugin.

.github/workflow-samples/kotlin-dsl/build.gradle.kts

@@ -0,0 +1,29 @@
+plugins {
+    `java-library`
+}
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    api("org.apache.commons:commons-math3:3.6.1")
+    implementation("com.google.guava:guava:31.1-jre")
+
+    testImplementation("org.junit.jupiter:junit-jupiter:5.8.2")
+}
+
+tasks.test {
+    useJUnitPlatform()
+}
+
+tasks.named("test").configure {
+    // Echo an output value so we can detect configuration-cache usage
+    println("::set-output name=task_configured::yes")
+
+    doLast {
+        if (System.getProperties().containsKey("verifyCachedBuild")) {
+            throw RuntimeException("Build was not cached: unexpected execution of test task")
+        }
+    }
+}