IVGCVSW-4317 Implement the Profiling Context Initialisation

IVGCVSW-4317 Implement the Profiling Context Initialisation

* Call CreateBackendProfilingContext on each backend from Runtime passing
  an instance of the BackendProfiling interface.
* Modify the signature of CreateBackendProfilingContext to remove const
  and return a shared_ptr to BackendProfilingContext
* Add concrete BackendProfiling class.
* Store BackendProfilingContexts in Profiling service.

Signed-off-by: Colm Donelan <Colm.Donelan@arm.com>
Change-Id: I975eaa2093ae91fa623835f65f9e5b25eb65117a