Remove raw bundle handling api from the framework headers

Currently it still is possible to direct get (and use) the bundle pointers through (e.g.):
- framework_getBundles
- framework_getBundleById
- celix_framework_getFrameworkBundle

These function are not thread safe.

There needs to be removed, so that only the celix_framework_useBundle variant can be used. The latter ensure that bundles are locked for uninstall while being used.

This will need some significant refactoring.