MapClientService Obex Unit tests

Create a framework for unit testing obex operations for use in
validating obex requests againgst a fake obex server.
The tests added here verify normal operation of several get and put
requests.

Bug: 190851901
Test: atest BluetoothInstrumentationTests
Tag: #stability
Change-Id: Iddfe6727f57d9b28ab365e7606932ac7a6913899