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/gradle-plugin/plugin/build.gradle

@@ -0,0 +1,60 @@
+/*
+ * This file was generated by the Gradle 'init' task.
+ *
+ * This generated file contains a sample Gradle plugin project to get you started.
+ * For more details take a look at the Writing Custom Plugins chapter in the Gradle
+ * User Manual available at https://docs.gradle.org/7.3/userguide/custom_plugins.html
+ * This project uses @Incubating APIs which are subject to change.
+ */
+
+plugins {
+    // Apply the Java Gradle plugin development plugin to add support for developing Gradle plugins
+    id 'java-gradle-plugin'
+}
+
+repositories {
+    // Use Maven Central for resolving dependencies.
+    mavenCentral()
+}
+
+testing {
+    suites {
+        // Configure the built-in test suite
+        test {
+            // Use JUnit Jupiter test framework
+            useJUnitJupiter('5.7.2')
+        }
+
+        // Create a new test suite
+        functionalTest(JvmTestSuite) {
+            dependencies {
+                // functionalTest test suite depends on the production code in tests
+                implementation project
+            }
+
+            targets {
+                all {
+                    // This test suite should run after the built-in test suite has run its tests
+                    testTask.configure { shouldRunAfter(test) } 
+                }
+            }
+        }
+    }
+}
+
+gradlePlugin {
+    // Define the plugin
+    plugins {
+        greeting {
+            id = 'org.example.gradle.plugin.greeting'
+            implementationClass = 'org.example.gradle.plugin.GradlePluginPlugin'
+        }
+    }
+}
+
+gradlePlugin.testSourceSets(sourceSets.functionalTest)
+
+tasks.named('check') {
+    // Include functionalTest as part of the check lifecycle
+    dependsOn(testing.suites.functionalTest)
+}