Ability to dynamically set route key in UseConventionalRouting

[saithis]

Is your feature request related to a problem? Please describe.

Currently I have to add a config line per message dto to specify the route key.

            opts.PublishMessage<DummyEvent1>().ToRabbitRoutingKey("my.app", "my.app.events.dummy1");
            opts.PublishMessage<DummyEvent2>().ToRabbitRoutingKey("my.app", "my.app.events.dummy2");

Describe the solution you'd like

Similar to ExchangeNameForSending I would like a RouteKeyForSending in UseConventionalRouting.
I'm not hung up on the name of this method, maybe RabbitRoutingKeyForSending would be better to keep the similarity to ToRabbitRoutingKey.

Describe alternatives you've considered

• Not use wolverine - but I want to
• Don't use route keys, but that seems like a bad idea
• Specify each and every Dto manually in the config... feels error prone if you forget one and it isn't a convention anymore
• Do reflection magic to dynamically build the opts.PublishMessage<DummyEvent2>().ToRabbitRoutingKey("my.app", "my.app.events.dummy2"); calls. This would probably be my go to, if the feature request is rejected.

Additional context

I'm using the RabbitMQ transport and want to use topics with route keys

[jeremydmiller]

@saithis I'm happy to take a pull request for this if it's important to you. Within the next couple weeks, we'll add better documentation on "build your own message routing conventions and just do whatever the hell you want". The capability is there, just not doc'd.