Macros don't work in Mdoc or when imports are nested

[ollyw]

When trying to update the zio documentation and using the latest zio-macros, there is an issue that is caused because mdoc wraps code snippets in objects or classes, with the imports inside the class. The error is:

error: ...docs/howto/mock_services.md:188:2: exception during macro expansion: 
scala.reflect.macros.TypecheckException: not found: type ZIO
        at scala.reflect.macros.contexts.Typers.$anonfun$typecheck$3(Typers.scala:44)
        at scala.reflect.macros.contexts.Typers.$anonfun$typecheck$2(Typers.scala:38)
        at scala.reflect.macros.contexts.Typers.doTypecheck$1(Typers.scala:37)
        at scala.reflect.macros.contexts.Typers.typecheck(Typers.scala:51)
        at scala.reflect.macros.contexts.Typers.typecheck$(Typers.scala:32)
  | => dat scala.reflect.macros.contexts.Context.typecheck(Context.scala:18)
	at scala.reflect.macros.contexts.Context.typecheck(Context.scala:18)
	at zio.macros.core.ModulePattern$ZIOExtractor.unapply(ModulePattern.scala:31)
	at zio.macros.core.ModulePattern$$anonfun$extractCapabilities$1.applyOrElse(ModulePattern.scala:152)
	at zio.macros.core.ModulePattern$$anonfun$extractCapabilities$1.applyOrElse(ModulePattern.scala:151)
	at scala.collection.immutable.List.collect(List.scala:308)
	at zio.macros.core.ModulePattern.extractCapabilities(ModulePattern.scala:151)
	at zio.macros.core.ModulePattern.extractCapabilities$(ModulePattern.scala:149)
	at zio.macros.accessible.Macro.extractCapabilities(Macro.scala:23)
	at zio.macros.accessible.Macro.apply(Macro.scala:49)

Here is a simple snippet to recreate:

The following fails:

object Foo {

  import zio._

  trait AccountEvent

  import zio.macros.annotation.{ accessible, mockable }

  @accessible
  @mockable
  trait AccountObserver {
    val accountObserver: AccountObserver.Service[Any]
  }

  object AccountObserver {
    trait Service[R] {
      def processEvent(event: AccountEvent): ZIO[R, Nothing, Unit]
    }
  }
}

Moving the import outside the object succeeds:

import zio._

object Foo {

  trait AccountEvent

  import zio.macros.annotation.{ accessible, mockable }

  @accessible
  @mockable
  trait AccountObserver {
    val accountObserver: AccountObserver.Service[Any]
  }

  object AccountObserver {
    trait Service[R] {
      def processEvent(event: AccountEvent): ZIO[R, Nothing, Unit]
    }
  }
}