SharedMemory API changes

Hides getFd & getFileDescriptor due to lifecycle concenrs.
Adds ASharedMemory_dupFromJava to allow sharing a shared
memory region between Java & Native as safe as possible.
Mis-use results in an FD leak instead of double-close.

Bug: 64394076
Test: SharedMemory CTS tests
Change-Id: I01a5eb978fc4e99559a79baac75754c32f13bdc4
7 files changed