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/java-toolchain/build.gradle

@@ -0,0 +1,17 @@
+plugins {
+    id 'java'
+}
+
+java {
+    toolchain {
+        languageVersion = JavaLanguageVersion.of(16)
+    }
+}
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    testImplementation('junit:junit:4.13.2')
+}