Add explicit execution context configuration

[retriku]

Adds configurable execution context while creating RabbitClient. Closes issue #694

[jbwheatley]

Yeah, think this looks like the most sensible way to add a configurable ExecutionContext 👍

You will unfortunately have do some work to get mima to pass - I think you can do this by new functions with the added argument and deprecating/making package private the old one. i.e.

@deprecated("use other apply method with configurable execution context", "4.1.1")
private[interpreter] def apply[F[_]: Async](
      config: Fs2RabbitConfig,
      dispatcher: Dispatcher[F],
      sslContext: Option[SSLContext] = None,
      saslConfig: SaslConfig = DefaultSaslConfig.PLAIN,
      metricsCollector: Option[MetricsCollector] = None,
      threadFactory: Option[F[ThreadFactory]] = None
  ): F[RabbitClient[F]] = ???

def apply[F[_]: Async](
      config: Fs2RabbitConfig,
      dispatcher: Dispatcher[F],
      sslContext: Option[SSLContext] = None,
      saslConfig: SaslConfig = DefaultSaslConfig.PLAIN,
      metricsCollector: Option[MetricsCollector] = None,
      threadFactory: Option[F[ThreadFactory]] = None,
      executionContext: Option[F[ExecutionContext]] = None
  ): F[RabbitClient[F]] = ???

[retriku]

Hi @jbwheatley! I do not know how to solve these migration issues. Maybe we need to increment major version?

[jbwheatley]

ah I think you're right, can't get it to work myself either. Default arguments are messy to work with 😿
I think in the future I'd consider replacing the client apply methods with a builder pattern.

Thanks for doing the legwork on this PR, if you have the time it would be great if we could go back to just adding the argument to the methods as you had it originally, and then we'll go for a 5.0.0 release

[retriku]

I introduced builder for RabbitClient. Please, review

[jbwheatley]

Awesome, the builder stuff is great 👍

Can you keep the existing apply and resource methods on RabbitClient, and deprecate them - pointing to the new builder class? That makes it easier for people to make the change when they upgrade.

[retriku]

@jbwheatley done!