Specify module for upf registration in config

There are 3 manual planner registrations:

    env.factory.add_engine(
        "aries", "libs.aries.planning.unified.plugin.up_aries", "Aries"
    )
    env.factory.add_engine(
        "aries-linear", "libs.aries.planning.unified.plugin.up_aries", "Aries"
    )
    env.factory.add_engine(
        "aries-insertion", "libs.aries.planning.unified.plugin.up_aries", "Aries"
    )

Add an optional class path for this, e.g., libs.aries.planning.unified.plugin.up_aries.Aries.