Add DynamicPropertyContributor

Currently DynamicPropertyRegistry can be used as a parameter on @Bean methods or test methods annotated with @DynamicPropertySource. If we have a DynamicPropertyContributor type we could return it. This would also allow us to ensure that TestcontainersLifecycleBeanPostProcessor could initialize them early.

The code would look like this:

@Bean
DynamicPropertyContributor dynamicPropertyContributor() {
    return (registry) -> {
            registry.add("spring.data.redis.host", redis()::getHost);
            registry.add("spring.data.redis.port", redis()::getFirstMappedPort);
    }
}

Start by reading DynamicPropertyRegistry, the @DynamicPropertySource handling, and TestcontainersLifecycleBeanPostProcessor. Trace how @Bean methods and test methods currently receive registries. Done means a DynamicPropertyContributor can be returned from a bean method and is initialized early enough for the lifecycle post-processor to use it.