Multiple MQTT client connections.

[ckapop]

Issue description

Is it possible to have more than one client to connect to different servers? I need to publish messages on 2 different brokers. I only see one mqtt.client.server-uri {type: String) configuration variable.

[ckapop]

Perhaps doing something like the http-client does using low level client?
public GithubLowLevelClient(@Client(id = "github") HttpClient httpClient, GithubConfiguration configuration)

or declarative client?

@Client(id = "github") 
@Header(name = USER_AGENT, value = "Micronaut HTTP Client") 
@Header(name = ACCEPT, value = "application/vnd.github.v3+json, application/json") 
public interface GithubApiClient {

    @Get("/repos/${github.organization}/${github.repo}/releases") 
    Publisher<GithubRelease> fetchReleases(); 
}

Could micronaut-mqtt do something similar?