memory: IAllocator is always binderized.

Benefits:
- single process allocates all of the shared memory (allows us to get
  statitistics).
- prevents us from having to open up the allocator in passthrough mode
  forever.
- prevents us from having to include/require android.hidl.memory@1.0-impl
  elsewhere

Bug: 32185232
Test: hidl_test
Change-Id: I37be6a4afb14a79df457e166aa4b99de416b8f40
4 files changed