Add microsphere-build-example sub-module and update testing setup

[mercyblitz]

This pull request introduces a new example module to the project and modernizes the build and CI workflows. The main focus is to provide a minimal example project (microsphere-build-example) that exercises the parent POM's build profiles and plugins, as well as to enhance CI by adding code coverage reporting and updating GitHub Actions to use the latest versions. Additionally, documentation and Maven wrapper configuration are improved for better usability and reproducibility.

New Example Module:

• Added a new microsphere-build-example module with its own pom.xml, a sample service (ExampleService.java), unit tests (ExampleServiceTest.java), and AsciiDoc documentation to demonstrate and validate build profiles and plugins from the parent POM. [1] [2] [3] [4]

CI/CD Workflow Improvements:

• Updated .github/workflows/maven-build.yml to:

  • Restrict push builds to the dev branch and expand pull request builds to include main, dev, and release branches.
  • Use the latest actions/checkout@v5 and actions/setup-java@v5.
  • Switch to the Maven wrapper (./mvnw) and activate test, docs, and coverage profiles by default.
  • Add a step to upload code coverage results to Codecov. [1] [2]

• Updated .github/workflows/merge-main-to-branches.yml to use actions/checkout@v5 for consistency and improved security. [1] [2]

Build Tooling and Documentation:

• Added and configured the Maven wrapper in .mvn/wrapper/maven-wrapper.properties for reproducible builds.
• Updated README.md to include a Codecov badge, reflecting the new code coverage reporting.

[codecov]

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