Add a way to cleanly override sbt plugin versions

[henryxparker]

Currently there is no simple command to override a plugin version.
If plugin A depends on plugin B, plugin B is imported automatically.
If the project already imported B but at an earlier version it will be evicted to the newer version.
Now lets say that A works fine with both versions of B, but the newer version of B breaks the build.
Currently, you must do something like this in the plugins.sbt

dependencyOverrides += {
  val sbtV = (pluginCrossBuild / sbtBinaryVersion).value
  val scalaV = (update / scalaBinaryVersion).value
  sbt.Defaults.sbtPluginExtra("com.twitter" % "scrooge-sbt-plugin" % "21.4.0" , sbtV, scalaV)
}

This is basically pulled directly from addSbtPlugin, with the only difference being that it goes into dependencyOverrides

  def addSbtPlugin(dependency: ModuleID): Setting[Seq[ModuleID]] =
    libraryDependencies += {
      val sbtV = (pluginCrossBuild / sbtBinaryVersion).value
      val scalaV = (update / scalaBinaryVersion).value
      sbtPluginExtra(dependency, sbtV, scalaV)
    }

So I figured it might be nice to add another set of methods akin to addSbtDependency
I figured overrideSbtPluginDependency or simply overrideSbtPlugin, but I'm open to suggestions