[21324] Adapt example generation to Fast DDS examples refactor

[JesusPoderoso]

Description

The Fast DDS examples have been refactored, making them homogeneous and more self-explained, with an improved README markdown file and best practices usage.
This PR introduces the same structure in the Fast DDS Gen generated examples.
Tested locally

Contributor Checklist

• Commit messages follow the project guidelines.
• N/A Tests that thoroughly check the new feature have been added/Regression tests checking the bug and its fix have been added; the added tests pass locally
• N/A New feature has been documented/Current behavior is correctly described in the documentation.
• N/A Applicable backports have been included in the description.

Reviewer Checklist

• The PR has a milestone assigned.
• The title and description correctly express the PR's purpose.
• Check contributor checklist is correct.
• Check CI results: changes do not issue any warning.
• Check CI results: failing tests are unrelated with the changes.