Add IMemoryToken and the HidlMemoryToken

The IMemoryToken is an interface which composes shared memory.
It provides a get() method, which returns an instance of hidl_memory
that always refer to the same memory.

The HidlMemoryToken is an implementation of the IMemoryToken.

Bug: 69640337
Test: hidl_test
Change-Id: Idf3a090213be8cb315134143cb81e1d7df91b4a2
5 files changed