Prototype Service factory

# Prototype service factory

Add support for registering and using prototype service factories for C and C++.
Also add support registering and using bundle service factories for C++.

# Background

[Chapter 5.9 "Service Factory" of the OSGi 8 spec](https://docs.osgi.org/specification/osgi.core/8.0.0/framework.service.html#framework.service.serviceFactory) mentions 3 types of scoped service objects:
- singleton: A normal service
- bundle: Create service instance per requesting bundle
- prototype; Create service instance per request

Apache Celix currently only supports the singleton scoped services and bundle scoped service factory (note that OSGi spec 5 only has a bundle scoped service factory).