[AXS-31] PIP API

[bernardoaraujor]

Policy Information Point coordinates the determination of attribute values used by the PDP.

PIP directory structure on repository must look like the following:

access/pip/
├── pip.c
└── pip.h

API Requirements:

• PIP API must consume custom callbacks for Data Acquisition in a platform agnostic way.
• PIP header (access/pip/pip.h) must expose functions to be used by Access Supervisor.

[strahinjagolic]

Done in f39fac66684997b6fba0505720a3e97f8ebf4fa4