Provide BundleContext through framework services

Currently the framework services

Framework.CREATE
Framework.INIT
Framework.ACTIVE

have a value that is internal to the framework and cannot be used by AS7.

The SYSTEM_BUNDLE and SYSTEM_CONTEXT services provide the value they suggest. However these are internal to the framework and suggest but don't guarantee a certain framework state.

This should be changed such that the system BundleContext is available through the respective framework services