maven_jar dependencies no longer work, as of #523

#523 broke dependencies on jars with macros (scalactic, scala-logging, shapeless, scalatest). I'm using `maven_jar` and for the dependencies that have macros, I use `@the_dependency//jar:file`. That no longer works, because `:file` doesn't have `JavaInfo`. Removing `:file` makes the compiler fail. What's the new recommended way of importing e.g. scalatest?

Start by reading the change in #523 and the issue's maven_jar examples, especially @the_dependency//jar:file and the JavaInfo failure. Compare the old and current dependency-import behavior for macro jars such as scalactic, scala-logging, shapeless, and scalatest; done means identifying and documenting a working import path.

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