Make it possible to use AsciiDoc attributes directly in the ConfigDocDefault annotation. This is especially useful to pass Maven properties as AsciiDoc attributes to the config properties as a default value for the documentation.

For example, we now define the keycloak.docker.image in a central place, however we lost the default value in the documentation. With this change we can also use AsciiDoc attributes as default value again for the documentation.

This should cover the initial idea from @gsmet, see #51024 (comment)

Locally this rendered the default value again for the Keycloak Docker image

DEV SERVICES OVERVIEW

• Compose Dev Services -> updated most examples ✅
• AMQP -> done ✅
• Apicurio Registry -> done ✅
• Databases -> took the same approach as the different Elasticsearch distributions with @asciidoclet ✅
• Kafka -> version centrally set in the extension itself for each provider
• Keycloak -> done ✅
• Kubernetes -> N/A - different flavours, so did not change anything here
• LRA -> done ✅
• MongoDB -> done ✅
• RabbitMQ -> done ✅
• Pulsar -> done ✅
• Redis -> done ✅
• Vault -> N/A - Quarkiverse
• Infinispan -> done ✅
• Elasticsearch -> multiple distributions possible, default image per distribution already listed in the JavaDoc with @asciidoclet ✅
• Observability -> version centrally set in the extension itself