Move Launchpad API embedding to launchpad base bundle

Currently the Launchpad API classes are in the Launchpad Base launcher code (standalone app or web app) and are "inherited" through the class loader hierarchy by the launchpad base bundle and exposed through system bundle exports into the OSGi Framework. This would be ok, if the launcher would actually use/require the launchpad API. This is not the case.

On the other hand, this setup prevents updating existing Sling setups with a new launchpad base bundle because newer builds require up-to-date launchpad API.

Since the launcher does not use the launchpad API it is more appropriate to actually include the launchpad API with the Launchpad Base bundle.