Replacement for gdbclient

 Differences between this implementation and the old one:
 1. Resolves symbols/gdb based on device information (lunch
    target is irrelevant)
 2. Works with downloaded from build-server symbols
 3. Does not require user to specify exe file - detects it automatically

Change-Id: I4e7ce0a51868634593a9f104fe3f2fa67b54ca9f