Initial import of HAL-layer tests for bluedroid.

Initial import of HAL-layer tests for bluedroid.

The test cases are in cases/, the support infrastructure for the
tests are in support/. Initially, as new test cases are being added
for different functional areas (e.g. BT socket) we'll need to also
write support functions to make those tests easier to write.
Over time, however, the support functions will be complete enough
that writing additional tests won't require also writing support
routines.

Change-Id: I54abb1011ca5132834a334cc256e3ff18cc20cbb