Make debezium-examples testable with CI/CD [DBZ-2371]

Migrated from [DBZ-2371](https://issues.redhat.com/browse/DBZ-2371)

I started a small PoC to find out how we could make updates to debezium-examples testable and easier + safer to update to newer versions by having CI/CD tests to validate changes and that examples still work.

[https://github.com/debezium/debezium-examples/compare/master...rk3rn3r:make-examples-testable-poc]

suggested process:
* migrate markdown documents to asciidoc (can be automated using pandoc), in order to extract example bash calls to scripts and then include script content in asciidoc
* either switch to asciidoc as default or use CI/CD to build markdown from asciidoc
* externalize all bash / test code calls to scripts and setup CI/CD automation to verify examples are working
* setup CI/CD pipeline to automatically test changes to debezium-examples
* make DEBEZIUM_VERSION a variable where it's hardcoded

Start by reviewing the linked make-examples-testable-poc comparison and the existing markdown examples. Define the CI/CD approach around the proposed script extraction, example verification, and DEBEZIUM_VERSION variable; done means the examples are automatically tested and safer to update.

Written by the indexing model from the issue text.