Add Dockerfile and GitHub workflow generators to Gradle plugin

[Copilot]

Adds two code generation tasks to the microservice Gradle plugin: one for producing a Dockerfile, another for a full CI/CD GitHub Actions workflow that builds, publishes, creates Docker images, and cuts GitHub releases.

New tasks

• generateDockerfile — Emits a Dockerfile with configurable baseImage, port, and jvmArgs. Copies the shadow JAR (*-all.jar) into a GraalVM-based image by default.
• generateWorkflow — Emits .github/workflows/publish.yml with the full pipeline: Gradle build → checks → Maven publish → Docker build+push to GHCR → GitHub Release with JAR artifacts. Supports optional moduleRegex for filtering release JARs.

Usage

// In consumer project — tasks are registered automatically by the plugin
// Run with defaults:
//   ./gradlew generateDockerfile
//   ./gradlew generateWorkflow

// Or configure:
tasks.named<GenerateDockerfileTask>("generateDockerfile") {
    baseImage.set("ghcr.io/graalvm/jdk-community:25")
    port.set(9090)
    jvmArgs.set(listOf("-Xmx512m"))
}

tasks.named<GenerateWorkflowTask>("generateWorkflow") {
    moduleRegex.set("my-service-paper.*-all\\.jar$")
}

Files changed

• task/GenerateDockerfileTask.kt — New abstract task with @Input/@OutputFile properties
• task/GenerateWorkflowTask.kt — New abstract task generating workflow YAML with Docker build/push, version extraction, release flag logic, and softprops/action-gh-release
• MicroservicePlugin.kt — Registers both tasks with conventions