Add finish() method to DataShare Read and Write Adapters

The finish() method is used to clear hard references after
the data copy has ended. This fixes a bug where the references are cleared before onError() is attempted to be called.

Test: CTS tests in followup CL
Bug: 157136368
Fixes: 157136368
Change-Id: If924fe388762831af90579e6b00bdf223230e203
4 files changed