aaudio: fix SHARED MMAP mode in server plus other bugs

Fixed some buffer miscalculations, and some NPEs in the close() code.
Added debugging and some general cleanup.
Fixed data conversion.
Fixed start/pause/flush in server.
Added reference counting in server for endpoints.
Programs can now be ran more than once.
General code cleanup.
Reconnect with service if server dies.
Move stop() logic into server for better synchronization.
Add sleep to prevent race condition when closing an MMAP stream.

Bug: 33398120
Test: two write_sine_callback.cpp can be run simultaneously
Change-Id: Ibb006215a498868c222228d675ff961d7e0bf514
Signed-off-by: Phil Burk <philburk@google.com>