We now register a BeanFactoryInitializationAotProcessor to generate the actuator endpoint content representing the application module structure at AOT processing time. That file is then preferred over bootstrapping an ApplicationModules instance when bootstrapping the endpoint.
Introduced ApplicationModulesExporter to render an ApplicationModules instances as JSON directly. To avoid a dependency to a JSON library and as we only have to be able to render rather simple arrangements, we just build up the JSON string ourselves.
ApplicationModulesEndpoint now caches the structure calculated once to avoid repeated work.
Introduce Spring Modulith Actuator module to expose the application module structure as Spring Boot actuator. This required a Spring Modulith Runtime module to be extracted from the Spring Modulith Observability one. The former now contains the auto-configured ApplicationRuntime and ApplicationModulesRuntime bean instances to be able to bootstrap a ApplicationModules asynchronously on application startup. The actuator module then contains a Spring Boot @Endpoint implementation consuming the ApplicationModules to render JSON describing the application module structure.
