Add emulator pipe integration

Replace the existing structure of only broadcasting over tcp with the
being able to broadcast over tcp or directly to the emulator pipes, so
the central handler thread now manages individual threads for each
potential client (network/pipe).

Test: manual (gcar_emu_x86-userdebug target with emulator)
Change-Id: I4363ae44cdc28a3d3eafa6044de7557c04a5c28b
(cherry picked from commit e191d74eb9c5859d90157a581f98de8abca71293)
4 files changed