Device: Initial bluetooth device API

Design:
    Have a simple memory map of devices for CLASSIC, LE, and DUAL.
This map will be managed by the DeviceDatabase and will eventually (not in this CL)
synchronize(using not yet submitted DeviceStorageApi) bonded devices to disk.

Bug: 139135297
Test: atest --host -t bluetooth_test_gd:DeviceTest bluetooth_test_gd:DeviceDatabaseTest bluetooth_test_gd:DualDeviceTest
Change-Id: I823b747aec5073feba5dc0f192f744329b43faf8