Add boolean dependencies between plugin and provider subpackages
    
    maven-surefire-plugin requires its providers to work correctly, yet it
    doesn't have any dependencies on them -- it relies on maven-local to
    pull in appropriate providers.
    
    In order to make Java buildroots smaller, maven-local will no longer
    require Surefire providers.  Instead, maven-surefire-plugin needs to
    conditionally require its providers, depending on whether particular
    testing framework package (JUnit, TestNG) is installed.